Lisa Marie Simpson is a fictional character in the animated television sitcom series The Simpsons. She is the middle child of the Simpson family. Voiced by Yeardley Smith, Lisa was born as a character in The Tracey Ullman Show short "Good Night" on April 19, 1987. Cartoonist Matt Groening created and designed her while waiting to meet James L. Brooks. Groening had been invited to pitch a series of shorts based on his comic Life in Hell, but instead decided to create a new set of characters. He named the older Simpson daughter after his younger sister Lisa Groening Bartlett. After appearing on The Tracey Ullman Show for three years, the Simpson family were moved to their own series on Fox, which debuted on December 17, 1989.

Intelligent, kind, and passionate about the planet and all living things, Lisa Simpson is the second child of Homer and Marge. Born Mother's Day, May 9, 1981, she is the younger sister of Bart, and the older sister of Maggie, at age 8. Lisa's high intellect and left-wing political stance creates a barrier between her and other children her age; therefore she is a bit of a loner and social outcast with few friends. Lisa is a vegetarian, a strong environmentalist, a feminist, and a Buddhist. Lisa's character develops many times over the course of the show: most notably, she becomes a vegetarian in season 7 and converts to Buddhism in season 13. A strong liberal and activist for peace, equality, and the environment, Lisa advocates for a variety of political causes (e.g. standing against apartheid in South Africa and supporting the Tibetan independence movement) which sets her against most of the people in Springfield. However, she can also be somewhat intolerant of opinions that differ from her own, often refusing to consider alternative perspectives and showing a feeling of self-righteousness. In her free time, Lisa enjoys many hobbies such as reading and playing the baritone saxophone and guitar. She has appeared in other media relating to The Simpsons – including video games, The Simpsons Movie, The Simpsons Ride, commercials and comic books – and inspired an extensive line of merchandise.

Yeardley Smith originally tried out for the role of Bart, while Nancy Cartwright (who was later cast as the voice for Bart) tried out for Lisa. Producers considered Smith's voice too high for a boy, so she was given the role of Lisa. In the Tracey Ullman Show shorts, Lisa was something of a "female Bart" who mirrored her brother's mischief, but as the series progressed she became a liberal voice of reason which has drawn both praise and criticism from fans of the show. Because of her unusual pointed hairstyle, many animators consider Lisa the most difficult Simpsons character to draw.

Originally conceived and described as simply the "middle child", without much other personality shown in her earliest appearances, Lisa has since undergone significant character expansion to the point where she is now commonly considered by critics, scholars and many fans to be one of the best-developed and most enduring female characters in television history. Like the rest of her family (especially Homer and Bart), Lisa is also considered an American cultural icon. TV Guide ranked her 11th (tied with Bart) on their list of the "Top 50 Greatest Cartoon Characters of All Time". Her environmentalism has been especially well-received; several episodes featuring her have won Genesis and Environmental Media Awards, including a special "Board of Directors Ongoing Commitment Award" in 2001. People for the Ethical Treatment of Animals (PETA) included Lisa on their list of the "Most Animal-Friendly TV Characters of All Time". Yeardley Smith won a Primetime Emmy Award for Outstanding Voice-Over Performance in 1992, and Lisa and her family were awarded a star on the Hollywood Walk of Fame in 2000.

Lisa Simpson is an extremely bright, talented, highly accomplished and often ambitious child prodigy who is one of the five central characters of The Simpsons, alongside the rest of the show's titular family. The middle child of the family and the older daughter of Homer and Marge, Lisa has an older brother, Bart, and a younger sister, Maggie. Attending Springfield Elementary School as part of Miss Elizabeth Hoover's second-grade class, Lisa is one of its most academically advanced students (alongside other gifted pupils such as fourth graders Martin Prince and "Database"), often receiving praise from the faculty for her achievements, and constantly achieving top grades and winning first place in many school competitions held throughout the series, including spelling bees, essay contests and science fairs. She is often eclectic in her knowledge, which covers a wide range of subjects from astronomy to medicine, and her favorite subjects in school are usually depicted as being science, mathematics and music, although she also excels in many areas of academics generally.

The Simpsons uses a floating timeline in which the characters do not physically age. The show itself is perpetually set in the year of broadcast (except for occasional flashbacks and flashforwards). In several episodes, events have been linked to specific time periods, although this timeline has been contradicted in subsequent episodes. Lisa's date of birth was given in one episode, "Lisa's First Word" (season 4, 1992), as May 4, 1984, during the Summer Olympics; that same episode also establishes her first word to have been "Bart", and she herself as originally receiving preferential treatment from her parents over Bart. "Lisa's Sax" (season 9, 1997) explains the origin of Lisa's saxophone: things do not go well for Bart on his first day of school, causing him to become depressed, and it is during discussions of Bart's future that the school's psychologist, Dr. J. Loren Pryor, realizes that the young Lisa is very intelligent, telling Homer and Marge that they need to nurture her gifted spirit, with Homer later discovering that a musical instrument is a way to encourage a gifted child, and subsequently sacrificing money originally intended for an air conditioner to buy Lisa her first saxophone. Nevertheless, Homer and Marge's attention would ultimately revert to being firmly on Bart and, later, Maggie, due to the respective antics of each having become increasingly problematic over time, thus causing a lack of nurturing for Lisa – which in turn has gradually caused her to feel "overlooked" on at least one occasion – and instead leading her to largely raise herself. The episode "That '90s Show" (season 19, 2008), however, contradicts much of the established backstory; for example, it presents Homer and Marge as being childless in the early 1990s. Despite this, Lisa is always portrayed as being 8 years old, making, for example, one potential year of birth 1981 based on the show's premiere having been in 1989. The series's canon would furthermore eventually settle on her true month and day of birth as being May 9, on account of "My Sister, My Sitter" (season 8, 1997) establishing her to be "two years and 38 days" younger than Bart. In the season 11 finale "Behind the Laughter" (2000), Lisa tells the show's viewers about having unwillingly been given "anti-growth hormones" by Homer and the producers to have her physical age permanently kept the same; however, that episode is considered non-canon due to its mockumentary and alternate history style.

Lisa is a lover of music, with jazz as her favorite genre; she specifically singles out Miles Davis's 1957 album Birth of the Cool as her favorite album. She enjoys and excels at playing the saxophone, having become friends with jazz musician Bleeding Gums Murphy, whom she regards as an idol. Murphy helps pull Lisa out of her depression in "Moaning Lisa" (season 1, 1990). She is later deeply saddened by Murphy's death in "'Round Springfield" (season 6, 1995). She also enjoys public broadcasting, including listening to National Public Radio, her favorite station, as shown in some episodes.

Lisa has had a few brief relationships with boys, including Ralph Wiggum in "I Love Lisa" (season 4, 1993), Nelson Muntz in "Lisa's Date with Density" (season 8, 1996) and Colin in The Simpsons Movie (2007). Bart's best friend Milhouse Van Houten has a crush on her, but despite dropping unsubtle hints about his feelings, he has been unsuccessful in winning her affection. Her voice actor Yeardley Smith said Muntz would make a good match for Lisa. In 2019, Simpsons showrunner Al Jean said he saw Lisa as being "possibly polyamorous" in the future. In the Season 23 episode "Holidays of Future Passed" (2011), Lisa is shown holding hands with an unnamed dark-haired woman in a photo, and then shown in a second photo where she is holding hands with two different women at once, suggesting polyamory; she later ends up with Milhouse. However, this episode is non-canon.

Lisa is the most intellectual member of the Simpson family (she has an IQ of 159), and many episodes of the series focus on her fighting for various causes. Lisa is often the focus of episodes with "a real moral or philosophical point", which according to former writer David S. Cohen is because "you really buy her as caring about it." Lisa's political convictions are generally left-wing and liberal, and she often contests others' views. She is a vegetarian, feminist, environmentalist and a supporter of gay rights, universal healthcare, and the Free Tibet movement. She also supports animal rights, though, likely due to her age, often typically sides more with cuter-looking animals generally considered harmless and innocent, such as rabbits or dolphins. In a special Christmas message for the UK in 2004, Lisa showed her support for Cornish nationalism, even speaking the Cornish language to get her message across. While she still continues to remain supportive of the general ideals of the Christian church in which she was raised, Lisa becomes a practicing Buddhist in the episode "She of Little Faith" (season 13, 2001) after she learns about the Noble Eightfold Path. An "End Apartheid Now" poster can be seen on her bedroom door during earlier seasons. She is extremely controlled by her ideals and noble, and she undergoes drastic changes when she or anyone else is immoral, such as renouncing Homer's last name and taking Marge's maiden name when she discovers that Homer bet against her in a crossword puzzle competition – namely, becoming "Lisa Bouvier" – in "Homer and Lisa Exchange Cross Words" (season 20, 2008).

Despite being a girl, Lisa is a skilled soccer player and ice hockey goaltender with a surprising level of hand-eye coordination, a good fighter, and an excellent gymnast due to her remarkably large head giving her perfect balance, demonstrating these talents most prominently in "Marge Gamer" (season 18, 2007), "Lisa on Ice" (season 6, 1994), many episodes throughout the series featuring her and Bart's sibling rivalry such as "Bart vs. Thanksgiving" (season 2, 1990), "My Sister, My Sitter" (season 8, 1997), "The Great Wife Hope" (season 21, 2009) and "The Greatest Story Ever D'ohed" (season 21, 2010), and "Little Girl in the Big Ten" (season 13, 2002), respectively; however, she has limited dancing talent, a problem that she has usually been shown to rectify only with the help of unconventional aids, such as undersole electronics in "Last Tap Dance in Springfield" (season 11, 2000) or second-hand smoke in "Smoke on the Daughter" (season 19, 2008). She also displays a surprising amount of skill in driving, especially for a child her age, sometimes even taking the wheel whenever either of her parents end up distracted from driving themselves, as shown, for example, in the season nine episode "Bart Star" (1997), and, despite being too young to actually hold a driving license, having her own electric car as first seen in the video game The Simpsons: Road Rage (2001), in addition to her bicycle that she is shown riding at certain other times (such as, most frequently, in the show's opening sequence). Furthering her driving talent, she is also shown entering a KF1 racing competition in "Lisa Gets an F1" (season 35, 2024), which she proficiently wins, similarly to Bart in "Saturdays of Thunder" (season 3, 1991), and has, on very rare occasions such as in some of the original Tracey Ullman Show shorts and in the couch gag for both "Homer vs. Dignity" (season 12, 2000) and "Trilogy of Error" (season 12, 2001), additionally been shown to demonstrate skateboarding skills comparable to those of Bart himself.

Matt Groening conceived Lisa and the rest of the Simpson family in 1986 while waiting in the lobby of producer James L. Brooks's office. Groening had been called in to pitch a series of animated shorts for The Tracey Ullman Show and had intended to present an adaptation of his Life in Hell comic strip. When he realized that animating Life in Hell would require him to rescind publication rights, Groening went in another direction, hurriedly sketching his version of a dysfunctional family, named after members of his own family. Lisa was named after Groening's younger sister, but little else was based on her. In The Tracey Ullman Show shorts, Lisa displayed none of the intelligence for which she later became known. She was more of a "female Bart" and was originally described as simply the "middle child", without much personality.

Lisa made her brief debut with the rest of the Simpson family on April 19, 1987, in The Tracey Ullman Show short "Good Night", and was the first identified family member, being the only character whose name is mentioned in the short, by Marge. On December 17, 1989, the shorts were adapted into The Simpsons, a half-hour series on the Fox Broadcasting Company, with Lisa and the rest of the Simpson family becoming the central characters on this new show.

The entire Simpson family was designed to be easily recognized in silhouette. The characters were initially crudely drawn because Groening had submitted rough sketches to the animators, expecting them to clean them up and to refine the designs; instead, the animators simply traced over his original drawings. Lisa's early design, featured in the first shorts, included spikier hair with a varying number of points of varying lengths; this was later standardized to eight much gentler points when seen from the side or, occasionally, ten in the case of a completely anterior or posterior view, with the angular gradient of the points being set at no less than 90 degrees for each point. Lisa's physical features are generally unique. In some early episodes, minor background characters occasionally had a similar hairline. However, in the later seasons, no character other than Maggie shares her hairline. While designing Lisa, Groening "couldn't be bothered to even think about girls' hairstyles". At the time, Groening was primarily drawing in black and white; when designing Lisa and Maggie, he "just gave them this kind of spiky starfish hair style, not thinking that they would eventually be drawn in color".

To draw Lisa's head and hair, most of the show's animators use what they call the "three-three-two arrangement". It begins with a circle, with two curving lines (one vertical, one horizontal) intersecting in the middle to indicate her eyeline. The vertical line continues outside of the circle to create one hair point, with two more added towards the back of her head. Three more points are then added in front (in the direction Lisa is facing), with two more behind it. Several Simpsons animators, including Pete Michels and David Silverman, consider Lisa the most difficult Simpsons character to draw. Silverman explains that "her head is so abstract" due to her hairstyle, which is usually shown to be approximately chin- or occasionally shoulder-length. Due to her design, her hairline, as with Bart's and Maggie's, has the appearance of being fused directly to her head, and in "The Blue and the Gray" (season 22, 2011), they humorously address the lack of a visible border distinguishing their hair from their heads. Darryn King, writing for Vanity Fair in 2018, described Lisa's hairstyle as "an outward display of her inner complexities" and a "sunburst-do" that "[defies] the natural principles of geometry".

Some episodes depict Lisa's hair being styled out of its usual star shape, including: "22 Short Films About Springfield" (season seven, 1996), where it is neatly collapsed over her scalp following a botched haircut that arose from the need to remove chewing gum that had become stuck to her head; "The President Wore Pearls" (season 15, 2003), where she is given an Eva Perón–esque makeover by the school faculty following her election as school student body president; "Teenage Mutant Milk-Caused Hurdles" (season 27, 2016), where Marge applies makeup to her to hide a temporary acne problem that had been caused by an allergic reaction to cheap hormone-rich milk; "The Last Traction Hero" (season 28, 2016), following her appointment as school bus monitor by Principal Skinner after filming an incident on the bus with her smartphone; and "Sorry Not Sorry" (season 32, 2020), where she flattens her hair into the style of "The Rachel". On the commentary for "The President Wore Pearls" particularly, director Mike B. Anderson recalls that Lisa's makeover hairstyle in that episode was even more difficult to draw than her usual style, and that the animators drew it with a "wackier" appearance. In most flashforward episodes showing Lisa as an adult or a teenager, such as "Lisa's Wedding" (season six, 1995), "Bart to the Future" (season 11, 2000), "Holidays of Future Passed" (season 23, 2011), "Days of Future Future" (season 25, 2014) and "Mr. Lisa's Opus" (season 29, 2017), her hair points are generally depicted in a frilled, "wavy" style, primarily to emphasize more of her maturity and self-esteem.

Lisa is four feet and two inches (1.27 m) tall, and usually wears the same everyday regular outfit, the latter being a trait typical of most The Simpsons characters, including the rest of her family. Her outfit consists of a strapless red-orange dress with a zigzag hem (resembling, and occasionally compared by herself and other characters to, a lampshade), matching Mary Janes and a white beaded pearl necklace (a gift from Marge for precociously achieving the ability to read at a 12th-grade level while still only in her infancy), and is sometimes completed with a red hair bow for certain special occasions; together with her hairstyle, this uniquely makes her the only Simpson family member not to include the color blue as part of her standard appearance, helping her stand out from them. Darryn King observes that the design of Lisa's dress also "gives her the silhouette of a shuttlecock" and, due to its hem, appears to have been inspired by the outfits worn by the characters of the 1960s Hanna-Barbera animated sitcom The Flintstones.

For other, more formal, occasions such as church and family outings, she usually (but not always) wears one of two different outfits: originally, this was usually a magenta long-sleeved dress with a ruffled collar and magenta pumps, later switching to the more commonly shown baby pink short-sleeved tutu dress with darker pink belt, dark pink collar, white socks, pink Mary Janes and occasionally a matching wide-brimmed hat. In addition, she has occasionally been shown wearing a third formal outfit consisting of a tall long-sleeved white dress with ruffled ankle-height hem trim, a white beaded pearl double necklace, a white flower in her hair and white pumps, beginning at the school talent show in the first act of "Lisa's Pony" (season three, 1991). At bedtime, she usually dresses in a short-sleeved turquoise nightgown with a frilly white collar and matching cuffs, as well as turquoise slippers (although she is sometimes seen going to bed barefoot instead); "Podcast News" (season 32, 2020), however, shows her wearing lilac footie pajamas with gray pads on the bottom of the feet. When swimming, she wears a magenta or red swimsuit.

She also wears invisible braces with a self-spraying fragrance from Calvin Klein.

While the roles of Homer and Marge were given to Dan Castellaneta and Julie Kavner because they were already a part of the Tracey Ullman Show cast, the producers decided to hold casting auditions for the roles of Bart and Lisa. Nancy Cartwright intended to audition for the role of Lisa, but disliked the character's bland description—Lisa was described simply as the "middle child"—and read for the role of Bart instead. Casting director Bonita Pietila brought Yeardley Smith in for an audition after seeing her performing in the play Living on Salvation Street. Smith was hesitant to audition for an animated series, but her agent had persuaded her to give it a try. Smith originally auditioned for the role of Bart but Pietila believed her voice was too high. Smith later recalled: "I always sounded too much like a girl, I read two lines as Bart and they said, 'Thanks for coming!'" Pietila offered Smith the role of Lisa instead. According to Darryn King, "If Dan Castellaneta's voice lends itself perfectly to Homer's oafishness, Nancy Cartwright's to Bart's impishness, and Julie Kavner's to Marge's harrumphing disapproval, there's a natural gentleness and warmth to Smith's voice that's essential to Lisa."

Smith and the show's writers worked to give Lisa a more defined personality, and she has developed greatly during the series. In her 2000 memoir My Life as a 10-Year-Old Boy, Cartwright wrote: "with the brilliant wit of the writers and the wry, in-your-eye, honest-to-a-fault interpretation, Yeardley Smith has made Lisa a bright light of leadership, full of compassion and competence beyond her years. Lisa Simpson is the kind of child we not only want our children to be but also the kind of child we want all children to be. But, at the time, on The Tracey Ullman Show, she was just an animated eight-year-old kid who had no personality."

Lisa is the only regular character voiced by Smith, who raises the pitch of her voice slightly for the role. In some earlier episodes she provided some of Maggie's squeaks and occasional speaking parts, and has voiced other characters on very rare occasions. Usually they are derivative of Lisa, such as Lisa Bella in "Last Tap Dance in Springfield" (season 11, 2000) and Lisa Jr. (Oovilu-Eeoo-Kitana-Wanjay) in "Missionary: Impossible" (season 11, 2000). Smith herself, however, is the only one among the six primary Simpsons cast members who is not allowed to voice other regular characters, having told Vanity Fair in 2018 that "The word came down: 'Yeardley, you're not allowed to be in the crowd unless Lisa Simpson is in the crowd. The timbre of your voice is too specific, and you always bleed through, and we can't have it.'"

Despite Lisa's fame, Smith is rarely recognized in public, which she does not mind. She said, "it's wonderful to be in the midst of all this hype about the show, and people enjoying the show so much, and to be totally a fly on the wall; people never recognize me solely from my voice." In a 2009 interview with The Guardian she commented that "It's the best job ever. I have nothing but gratitude for the amount of freedom The Simpsons has bought me in my life." Although Smith received a Primetime Emmy Award for Outstanding Voice-Over Performance in 1992, she considers it unimportant, saying "there's part of me that feels it wasn't even a real Emmy." The award is a Creative Arts prize not awarded during the primetime telecast and, at the time, a juried award without nominations. Still, Smith considers her work on the show a success. "If I had to be associated with one character in fiction," she said, "I will always be thrilled that it was Lisa Simpson." Matt Groening has described Smith as being very similar to Lisa: "Yeardley has strong moral views about her character. Some lines are written for Lisa that Yeardley reads and says, 'No, I wouldn't say that.'" Former Simpsons writer Jay Kogen praised her performance on the show, particularly in the episode "Lisa's Substitute" (season two, 1991), as able "to move past comedy to something really strong and serious and dramatic." Calling Lisa the show's "resident idealist and bleeding heart", and comparing her and most other residents of Springfield to Wile E. Coyote and the Road Runner respectively, King writes of Lisa's role as often "[setting] her up for regular disillusionment and crushed spirits". Additionally, "Lisa's Pony" (season three, 1991), "Lisa's First Word" (season four, 1992), "I Love Lisa" (season four, 1993), "Lisa's Wedding" and "'Round Springfield" (both season six, 1995), "Summer of 4 Ft. 2" (season seven, 1996), "Lisa's Sax" (season nine, 1997), and "Lisa the Tree Hugger" (season 12, 2000) are examples of other Lisa-centric episodes that have been cited as being emotionally resonating.

Until 1998, Smith was paid US$30,000 per episode for her work on The Simpsons. A pay dispute erupted in 1998, during which Fox threatened to replace the six main voice actors with new actors, going as far as preparing for casting of new voices. The dispute was ultimately resolved, and Smith's salary increased to $125,000 per episode until 2004 when the voice actors sought a further increase to $360,000 per episode. The issue was resolved a month later, and Smith earned $250,000 per episode. New salary negotiations took place in 2008, with the voice actors subsequently receiving approximately $400,000 per episode. Three years later, with Fox threatening to cancel the series unless production costs were cut, Smith and the other cast members accepted a 30 percent pay cut, down to just over $300,000 per episode. By 2016, Smith and the rest of the cast were each being paid $315,000 per episode, which, according to Variety, made them some of the highest-paid voice actors at the time.

Lisa is the only Simpson child – and furthermore one of only three characters, the others being Homer and Marge – to appear in every episode of The Simpsons. Despite this, however, she does not have lines in "Chief of Hearts" (season 21, 2010), "Moho House" (season 28, 2017) or "Carl Carlson Rides Again" (season 34, 2023), and furthermore features only in pictures instead of having an actual physical role (or even a mention) in the last episode's case, even though Smith is still credited at the end of all three of those episodes.

In The Tracey Ullman Show shorts, Lisa was something of a "female Bart": equally mischievous but lacking unique traits. As the series progressed, Lisa began to develop into a more intelligent and more emotional character. She demonstrates her intellect in the 1990 episode "Krusty Gets Busted" (season one), by helping Bart reveal Sideshow Bob's plot to frame Krusty the Clown for armed robbery in what Mike Reiss considered to be "one of the first episodes where her true intelligence is fully shown". Many episodes focusing on Lisa have an emotional nature, such as "Moaning Lisa" (season one, 1990). The idea for the episode was pitched by James L. Brooks, who wanted to do an emotional episode involving Lisa's sadness, to complement the many "jokey episodes" in the first season. The second season furthered the development of these traits significantly – with 1990's "Bart the Daredevil" and "Bart vs. Thanksgiving", and 1991's "Lisa's Substitute", "One Fish, Two Fish, Blowfish, Blue Fish" and "The War of the Simpsons" all featuring the most prominent demonstrations of such a move – although the third and later seasons would return to showing Lisa mostly as a typical eight-year-old girl, albeit one still with very high intelligence and well-developed emotions. Lisa's middle name, "Marie", was given to her by writer Greg Daniels, completing a cultural reference to the daughter of the "King of Rock and Roll", Elvis Presley.

The sixth-season episode "Lisa's Wedding" (1995) was the first to introduce Lisa's adoption of vegetarianism, albeit in a future context. In the seventh-season episode "Lisa the Vegetarian" (1995), she decides to permanently become a vegetarian in the then-present day as well, distinguishing her as one of the first primetime television characters to make such a choice. The latter episode was written by David S. Cohen (in his first solo writing credit), who jotted down the idea one day while eating lunch. Then-executive producer David Mirkin, who had recently become a vegetarian himself, quickly approved the idea. Several of Lisa's experiences in the episode are based on Mirkin's own experiences. The episode guest stars musician Paul McCartney, a committed vegetarian and animal rights activist. McCartney's condition for appearing was that Lisa would remain a vegetarian and would not revert the next week (as is common on situation comedies). The trait has, for the most part, stayed and is generally considered to have been one of the few permanent character changes made in the show; in keeping with this, many subsequent episodes appearing to feature Lisa still eating meat usually include dialogue handwaving that as actually being plant- or tofu-based – such as the Thanksgiving turkey served at Moe's by rock band R.E.M. at the end of "Homer the Moe" (season 13, 2001) – with the exception of appearances in flashback episodes such as "Fland Canyon" (season 27, 2016), where she unambiguously eats bacon in a flashback, or on deliberately accidental occasions such as those in "Lisa Gets an 'A'" (season ten, 1998), "Mommie Beerest" (season 16, 2005), "Papa Don't Leech" (season 19, 2008), and "The Food Wife" (season 23, 2011), where she is served oven-roasted cud, a pancake-wrapped sausage, barbecued chicken, and "pork chops 100 ways", respectively, by Marge, Bart, Lurleen Lumpkin and El Chemistri. Even in episodes after she becomes a vegetarian, however, there are still non-accidental instances where her dinner plate has meat, which she has usually nevertheless been seen to leave. However, more recent seasons – including in "The Food Wife" and in "You Won't Believe What This Episode Is About – Act Three Will Shock You!" (season 33, 2022), the latter in which she goes to eat prawns at Dead Lobster's "Prawn-A-Thon" with Marge, Bart and Maggie – have gradually established the trait to be surprisingly flexible, culminating in "Ae Bonny Romance" (season 35, 2023) prominently showing her eating a Scotch egg, albeit naïvely, at the Edinburgh Fringe Festival.

In the season 13 episode "She of Little Faith" (2001), Lisa undergoes another major character change by converting to Buddhism, this time at the insistence of both then-returning showrunner Al Jean and that episode's guest star, actor Richard Gere, the latter himself a practicing Buddhist. At the time, Buddhism was considered the "hippy religion" of many liberal-minded Millennials practicing vegetarianism (or even veganism), and Jean pitched the idea in order to further expand Lisa's personality. The series's writing staff became concerned about the episode's originality, arguing that the series had already explored religious themes in earlier episodes, but Jean assured them that the episode, written by Bill Freiberger (in his only writing credit for the series), would be about Lisa first-and-foremost, rather than Buddhism. Gere's main conditions for appearing also included that Buddhism should be portrayed accurately and that Lisa should also become a supporter of the Free Tibet movement like himself. Although the line "Free Tibet" itself as to have been spoken by her ultimately did not appear in the episode, Lisa has since subsequently agreed with Gere's sentiments in that episode in some of the series's later ones, and, since then, Lisa has officially remained a Buddhist, despite simultaneously still continuing to support Christianity and its ideals by agreement with Marge thanks to Gere's words of encouragement near the end of that episode.

Lisa plays the baritone saxophone, and some episodes use that as a plot device. According to Matt Groening, the baritone saxophone was chosen because he found the thought of an eight-year-old girl playing it amusing. He added, "But she doesn't always play a baritone sax because the animators don't know what it looks like, so it changes shape and color from show to show." One of the hallmarks of the show's opening sequence is usually a brief solo Lisa plays on her saxophone after being thrown out of music class. The Simpsons composer Alf Clausen said that the session musicians who perform her solos, including Terry Harrington and Kim Richmond, do not try to play at the second-grade level and instead "think of Lisa as a really good player." On her "Lifelong List of Things to Do" in The Lisa Book (2006), two of Lisa's stated goals are to "execute a pure glissando from second octave A upwards that causes people to weep at the sheer beauty of its sound" and "play a sax solo at the Playboy Jazz Festival while protesting the fact that [she is] there".

Lisa also has other extensive musical abilities: she has a powerful singing voice that she often uses (and with which she even enters a singing competition in "A Star Is Torn" and wins), and is a skilled multi-instrumentalist, besides saxophone, as she can also play bass (as shown in "Whacking Day"), guitar (as shown most notably in "Last Exit to Springfield" and "Million Dollar Abie"), and piano (as shown in "Miracle on Evergreen Terrace"). In addition, some more recent variations of the opening sequence depict her playing both those instruments (except the piano) and others including (but not limited to) a harp, violin, trumpet, tuba, and French horn. Lisa's singing voice, first heard at the end of the show's first aired episode, "Simpsons Roasting on an Open Fire" (1989), and then more prominently in "Moaning Lisa", is provided by Smith herself, and is generally similar to Smith's in real life, which Jean has described as being "very good". According to Smith, Lisa's normal speaking voice provides difficulty in allowing Smith to sing as her, leaving Smith theoretically only able to sing in "about four notes". There are several songs in some episodes, including "A Star Is Torn", which Smith has claimed were pitched too high for her real-life singing voice, which is generally a lower pitch; a later example would be "Super Star" in the season 23 finale "Lisa Goes Gaga" (2012). As a result of this, she usually alternates between Lisa's voice and her own real-life singing voice to provide Lisa with a more versatile singing range than Lisa's normal speaking voice is capable of. While Lisa's singing was already a relatively common occurrence prior to "The President Wore Pearls" (season 15, 2003), it has become increasingly more frequent since that episode at the insistence of Jean.

Reflecting on Lisa's character development in 2018, Smith said: "She's so beautifully fleshed out. In the animation, and the writing and, hopefully, in the performance, that I feel as though she exists quite separately from me. I really feel like—I honestly feel this—it's been such an honor to embody a character that I would look up to. And then, the icing on the cake is that other people look up to her too. She's so who I wish I could be."

Lisa is generally characterized as a charismatic, innovative, insightful, gifted, confident, free-spirited, smart, witty, independent, idealistic, musically inclined, cute, sweet, naïve, kind, caring, mature, usually well-behaved, often rebellious, often brave, sometimes narcissistic, sometimes envious, sometimes sassy, sometimes girly, sometimes mischievous, sometimes feisty, often playful, adorable, precocious, highly self-esteemed, sociable, and extremely intelligent girl who far exceeds the standard achievement level of children of her age range, steadfastly focusing on her goals and always striving to reach her potential. She is also regularly depicted as the moral center of both the Simpson family specifically and the show at large generally, and often acts as the voice of reason for both, often being, despite her young age, a good girl with a surprisingly strong sense of right, wrong and morality. She has a generally independent upbringing, with parental involvement from neither Homer nor Marge (who both tend to focus more on Bart and Maggie), leading to hobbies such as reading and research, music, equestrianism and horse management, and an interest in advanced studies. In many flashbacks to her infancy, she is depicted as already displaying advanced intellectual independence that ranges from changing her own diapers to solving complicated mathematical questions (and even being able to start speaking only a few months after being born), and in the present day is generally portrayed as having the most promising future not only of the Simpson children but also of virtually all the students of Springfield Elementary School (with the possible exception of Martin Prince), with Harvard University regularly being depicted as her main future higher education institution of choice (most recently, for example, in the season 29 episode "Mr. Lisa's Opus", where she is accepted into the university's college, and again in the season 32 episode "Mother and Child Reunion", as part of her eclectic series of higher education enrollments), despite a lack of encouragement from her family and a lack of resources on the school's behalf to fully cater to her needs, both of which she has often expressed disappointment with.

However, despite being a child prodigy, she often sees herself as a misfit within the Simpson family and other children precisely due to possessing an unusually high level of intelligence, and her popularity in school in particular is regularly influenced by some of the other students (including Bart), who regard her as a proud overachiever and introvert, leaving her with only a relatively small group of friends that consists mainly of other girls (such as her best friend, Janey Powell, and Allison Taylor) and sometimes also some nerdy boys nicknamed "The Superfriends". Additionally, she sometimes feels that her constant successes at school have gradually made it such that her accomplishments do not surprise or inspire as much as they used to anymore. Her school yearbook, first seen in the seventh-season finale "Summer of 4 Ft. 2" (1996), features photographs of her accepting such accolades as being "Miss Perfect Attendance", the school's "Grammar Rodeo Head Buckaroo", a lover of international culture and cuisine, and a teacher's pet. She also keeps a personal diary in which she records her thoughts. Despite her young age, Lisa is extremely passionate about ideologies and other social movements. She shows characteristics rarely seen in Springfield, including spirituality and commitment to peaceful ways, and is notably more concerned with world affairs than her life in Springfield, with her rebellion against social norms being depicted as constructive and heroic, yet she can be self-righteous at times. In "Lisa the Vegetarian", an increasing sense of moral righteousness leads her to disrupt her father's roast-pig barbecue, an act for which she later apologizes. Like most children her age, she thinks in images rather than words. Episodes often take shots at Lisa's idealism, and she herself, at times, has been depicted to resist certain situations merely for the sake of resisting them rather than due to any genuine ideological opposition. In "Bart Star" (season nine, 1997), Lisa, who is departing from her typically more genuine nature and apparently looking for a new cause to crusade over, defiantly declares that she, a girl, would like to join the football team. In the 1990s, it was considered odd to allow a girl to play football. However, when coach Ned Flanders reveals that several girls already play for the team, she hesitates and claims football is "not really [her] thing". She then expresses distaste about a ball made of pig's skin, but one of the girls informs her that their footballs are synthetic and that proceeds are donated to Amnesty International. Upset by being unable to gain moral superiority, Lisa runs off. Her comment about the ball's material also foreshadows the future experimentation with veganism that she decides to take up in season 32, though that has subsequently usually been shown to be more of an occasional feature rather than another permanent character change. Lisa's sense of faith is complex, as she can be very spiritual despite her skepticism of the supernatural, and her spiritual wariness contrasts juxtaposed with her more conformist mother. In "She of Little Faith", she decides to become a Buddhist after being appalled at how the First Church of Springfield allowed Mr. Burns to rebuild the church, which burned after being hit with Bart and Homer's rockets, with commercialism. Despite no longer actively following the Christian faith, she still is seen attending church in later episodes, and continues to support its ideals in response to initial words of encouragement by Richard Gere. She is, despite her skepticism, also interested in Wicca, mentioning on several occasions, including in The Simpsons Movie (2007) and "Rednecks and Broomsticks" (season 21, 2009), that, despite not being a true adherent of that movement, she nevertheless considers it to be "very empowering", hinting at a plurispiritualistic belief that does not just incorporate aspects of Buddhism and Christianity, and therefore suggesting a non-traditional, more introspective approach to spirituality, while others often have more traditional beliefs; she furthermore befriends three actual Wiccans in "Rednecks and Broomsticks", although their friendship ultimately remains temporary at Marge's insistence. "The Girl Who Slept Too Little" (season 17, 2005) revisits her skepticism and establishes her to also be a major believer in science, with her mentioning in that episode that, during her fear of the new cemetery temporarily established next to the Simpson house, she believed only in science, a stance soon briefly returned to in "The Monkey Suit" (season 17, 2006) in response to Springfield's controversial but ultimately short-lived ban on the teaching of science, which had been spearheaded by Flanders and Reverend Lovejoy, in that episode.

Despite Lisa's usual embrace of vegetarianism (and sometimes later of veganism, as aforementioned), her favorite food is fried shrimp (and previously also bacon), an example of flexible vegetarianism, and she is said to also occasionally eat Krusty Burgers while seeking to "invent a meatless hamburger that tastes as darn good" as part of her "Lifelong List of Things to Do". She also demonstrates, on occasion, and in a subversion of her usual support for animal rights, her fondness of at least the smell of cooked lobsters, as shown, for example, in the scene from "Homer's Enemy" (season eight, 1997) where Frank Grimes visits the Simpson house on Homer's invitation to see what the Simpson family are like, and further re-affirmed by herself in dialogue in a scene from "Lisa Gets an 'A'" (season ten, 1998) after witnessing Bart express dissatisfaction at being served with a vegetarian dinner instead of lobster due to Homer's newfound affection for a homegrown lobster named "Mr. Pinchy".

Lisa is said to have an IQ of 159, and in "They Saved Lisa's Brain" (season ten, 1999) she becomes a member of the Springfield chapter of Mensa. Even prior to becoming a Buddhist, Lisa at times is seen meditating. When unable to attend school due to a teachers' strike in "The PTA Disbands" (season six, 1995), she suffers "school withdrawal" symptoms because of the sudden lack of praise. She even demands that her mother grade her for no obvious reason. In Planet Simpson, Chris Turner writes that these traits, and certain others as aforementioned, make Lisa more realistic because "No character can aspire to realism without a few all-too-human flaws."

Although she is wise beyond her years, Lisa has typical childhood issues, sometimes requiring adult intervention. One episode to show this is "See Homer Run" (season 17, 2005) where she goes through a developmental condition which causes her to get into trouble at school. In "Lost Our Lisa" (season nine, 1998), she tricks Homer into allowing her to ride the bus alone, only to become hopelessly lost and in need of aid from her father. Chris Turner writes in Planet Simpson that incidents like this illustrate that "Even when Lisa's lecturing like a college professor or mounting yet another protest, she never becomes a full-grown adult trapped in a child's body." In The Simpsons and Philosophy: The D'oh! of Homer, Aeon J. Skoble states that although Lisa is an intellectual, she is still portrayed as a character who enjoys normal childhood and girl activities, plays with Malibu Stacy dolls, loves ponies, obsesses over teenage heartthrobs such as Corey Masterson, and watches The Itchy & Scratchy Show along with Bart. He writes, "One might argue that this is typical childhood behavior, but since in so many cases Lisa is presented not simply as a prodigy but as preternaturally wise, the fondness for Itchy & Scratchy and Corey seem to be highlighted, taking on greater significance. Lisa is portrayed as the avatar of logic and wisdom, but then she also worships Corey so she's 'no better [than the rest of us]'." When she becomes depressed over being unable to pursue her dreams as a musician due to inheriting her father's "stubby fingers" (affecting her dexterity slightly) and having to spend her time with Marge in being a homemaker, Lisa gives up on school and becomes a juvenile delinquent in "Separate Vocations" (season three, 1992). She is stopped by Bart who encourages her to keep proving people wrong and pursue her dreams as a musician.

Lisa has demonstrated an acute sense of emotion and sensitivity, both positive and negative, the latter in particular often involving bursting into tears whenever emotionally overwhelmed. First shown in the Season 1 episode, "Moaning Lisa", when Homer hurts his daughter's feelings midway in the episode, there has been a sizable portion of episodes featuring Lisa sobbing, to the point where it remains her most well-known, and continuously used, trait, alongside her vegetarianism and Buddhism. Later in that episode, she is depicted singing song lyrics containing the words "I'm the saddest kid in grade number two" and "My dad acts like he belongs in a zoo". It is not uncommon for each and every season to feature an episode where Lisa cries at some point, even silently. More positively, and also surprisingly common, is for her to at least giggle, grin or do both, even ever so slightly, when amused by something, demonstrating her sweetness and naïvety in an upbeat but subtle way.

Her laugh and "beautiful smile", the latter in both toothy and fully closed forms, are also major traits of her personality, and, like the aforementioned sobbing, are also extensively used, the former in a wide variety of comedic moments for which she is present and the latter whenever she is very happy, excited or posing for certain photographs. The former's contextual placement even reaches its most extreme in a scene from "Go Big or Go Homer" (season 31, 2019), where she is the only Simpson family member to find Springfield Nuclear Power Plant intern Mike Wegman's offensive comments about Bart's appearance funny, and ends up laughing uncontrollably – a sharp contrast to Bart's own emotional breakdown in that same scene, Marge's anger towards Mike, Homer's mild but horrified disdain, and Maggie's stoic ambivalence. An earlier example of an episode featuring scenes where Lisa laughs, but nobody else (not even Bart), is "Bart Sells His Soul" (season seven, 1995), where she remains upbeat even after finding out Bart "sold" his soul to Milhouse Van Houten and himself gradually became depressed, resentful and angry over it.

Despite her charisma, intelligence and mostly confident personality, Lisa occasionally worries that her family's dull habits will rub off on her, such as in "Lisa the Simpson" (season nine, 1998) she worries that the "Simpson Gene" will make her a dimwit later finding out the gene only goes through the male side (more specifically, affecting only the Y chromosome). She is often embarrassed and disapproving of her eccentric family: of her father's parenting skills and buffoonish personality; her mother's stereotypical image and social ineptitude; and her brother's delinquent and low-brow nature. More specifically, Lisa knows Homer and his behavior well, and is often able to ascertain whether he has ulterior motives or is carrying out actions beneficial mainly to himself, sometimes expressing hurt at his lack of genuine interest in spending time with either herself, her siblings, or Marge, and often showing serious concern for his physical health. Likewise, Lisa and Marge generally get along well, with both being logical and wise females to more impulsive and short-tempered males (Bart and Homer, respectively), although there have been moments of friction between the two – such as in "Lisa the Vegetarian" or "She of Little Faith", where Lisa finds Marge to be less than welcoming of her character development as Marge firmly believes Lisa is simply going through phases – and, similar to Homer, Lisa knows Marge very well and how she tends to act or think during certain moments, and also always aims to avoid Marge's fate. Despite all of this, however, she has usually good relationships with all of her immediate family members, and enjoys her mother's homemade waffles. Although they have many differences, Homer and Lisa maintain an affectionate relationship, with episodes like "Lisa the Greek" (season three, 1992) and "Bart on the Road" (season seven, 1996) depicting the bond between them often being cited as fan favorites. Homer is often oblivious to her talents but clearly respects her intelligence, such as when he supports her controversial research about Jebediah Springfield in "Lisa the Iconoclast" (season seven, 1996) because she's "always right about this kind of stuff." She is also concerned that Maggie may grow up to be like the rest of the family and tries to teach her complex ideas; their overall relationship is generally close and buddy-like due to Maggie's infant state, with Lisa often also enjoying Maggie's company and (unlike Bart) being able to enjoy sisterly activities with her. Chris Turner writes in Planet Simpson that "Lisa embarks on quests to find solace for her yearning spirit ... but the most reliable source of truth she finds is the one she always believed in: her family. It is from the other Simpsons that Lisa draws stability, meaning, contentment." Her loyalty to her family is most clearly seen in the flashforward "Lisa's Wedding" (season six, 1995), in which she must reconcile her love for them with the distaste of her cultured fiancé. In the episode "Mother Simpson" (season seven, 1995) she meets her paternal grandmother Mona Simpson for the first time. Mona is also well-read and articulate, and the writers used the character as a way to explain the origins of Lisa's intelligence.

Lisa's sense of right, wrong and morality often also leads her to contradict Homer, Bart and, on some occasions, Marge whenever they act reckless or idiotic, or do something illegal, forcing them back to righteousness out of fear for, in particular, her father and brother's own morality. In an argument, Lisa's ethical and logical viewpoints almost always give her the moral high ground, with her family also usually realizing Lisa to usually be in the right after they do something immoral, but, due to Homer's tendency to ignore her, sometimes using the excuse of age to send her to her room upon realizing that they are in the wrong. Lisa also shares a sibling rivalry with Bart (arising from a mutual sense of superiority, age-wise for Bart and intelligence-wise for Lisa, which has occasionally escalated to physical confrontations and revenge plots), however, to the point of even being shown to seriously injure him on many occasions dating back to their infancies when angered enough by his antics, and some episodes in earlier seasons even depicted Lisa herself with her usual intelligence but not yet as much maturity due to being more commonly shown feuding with him, such as, most prominently, in "There's No Disgrace Like Home" (season one, 1990), in which they are seen constantly electrocuting each other at Dr. Marvin Monroe's therapy clinic, and "Bart vs. Thanksgiving" (season two, 1990), where they fight at the dinner table over Bart's seemingly unintentional destruction of Lisa's centerpiece. She has, however, developed into a more practical being, yet her young age also makes her sense of right and wrong slightly malleable at times as she has herself been shown to engage in childish and reckless behavior, as well as mischief of her own, proving herself to be like any other Simpson when she wants to be, but more grounded and mature, and thereby still retaining her original "female Bart" traits albeit now in a more subtle form. Similarly to Bart with regard to Lisa and sometimes Maggie, and typical of most siblings in families, Lisa herself has also been shown throughout the series to sometimes tease Bart – including about his various crushes, sassing him for attention, attempting to scare him into doing things that she would like him to, and, in "Bart the Lover" (season three, 1992), over his writing of secret love letters to his then-teacher, Mrs. Edna Krabappel – but the two are often very close, sometimes to the point of giving each other a hug, with Lisa even outright helping Bart on many occasions, or at least consoling him in his times of need.

Some of the school's other students generally regard Lisa's lesser popularity than that especially of Bart's as being purposeful, unaware that, despite having her own group of friends, Lisa regularly yearns for more people like herself to befriend in other places due to having different hobbies from her usual friends. This trait is the primary focus of "Summer of 4 Ft. 2", in which, while on vacation in Little Pwagmattasquarmsettport with her family and Milhouse, she changes her personality to fit a more rebellious nature similar to that of Bart's, buys some correspondingly "cool" attire, and acquires another group of friends near Flanders's beach house. Despite her true academic nature being jealously revealed one night by Bart and his Fourth of July "yearbook stunt", and Lisa's own fears of subsequently being shunned by the beach house friends, the latter, to Lisa's surprise, continue to befriend her while she is still there, on account of her overall good nature rather than simply her overachievements (although this friendship ends up only being temporary). Additionally, in "The Girl on the Bus" (season 30, 2019), in one of the most prominent displays of her free spirit to date, she even subverts her usual loyalty to her family by seeking out another family to which she can relate more, at least culturally and intellectually, before eventually being caught trying to leave her home one night by a furious Marge.

Similarly to her friend-seeking, although her social movements are generally considered to be heroic, Lisa's reasoning is sometimes portrayed as being not solely to improve her world: a life of being overlooked by her family has also resulted in Lisa developing an attention-seeking trait and a desire to always be heard, even going to an excavation site for a new mall in "Lisa the Skeptic", for example, simply to complain about it, a situation where she has often been ignored further. Although she often seeks to force her beliefs on others due to a sense of moral superiority, she also displays a degree of tolerance for others' beliefs, a trait learned from Apu Nahasapeemapetilon. Lisa also usually opposes ignorance on others' behalf, believing only in the truth and usually being unable to be dissuaded no matter what it is, a trait learned from Marge.

Lisa is usually rational and thinks things through, but an occasional running theme in some episodes centered on her involves her displaying narcissism or envy that in turn can sometimes lead to extreme jealousy of rivals or with a lack of attention from either her parents or the school faculty. More specifically, she often considers Homer and Marge's usual favoritism for Bart and Maggie over her to be one such major point of jealousy, despite generally being the most well-behaved, mature and intelligent of the three Simpson children, and in spite of her and Homer's often good father-daughter relationship. Other areas she becomes jealous of are school generally and music. Lisa is extremely proud of being the best when it comes to her intelligence, her schoolwork and playing the saxophone, with recurring "straight A's" being another one of her strong points and she herself having briefly been promoted to the third grade, but she has been shown to become incredibly competitive and angry should a rival be able to match or try to surpass her in areas that she excels in despite many claims of needing a challenge or someone to relate to with the same issues. She is not used to being anything other than the best, and her resulting jealousy can at times make her act out in troublesome ways, including displaying a willingness to malleate her own principles if she asserts her pride to be at risk. One episode to show this is "Lisa's Rival" (season six, 1994), where she becomes jealous of then-newcomer Allison Taylor's skills and achievements to the point of trying to sabotage her entry in a diorama contest with help from Bart, although by the end of that episode the two girls finally make amends and decide to become close friends after discovering that they have more positive characteristics in common than they had thought. A later, more notable example of jealousy occurs in "Smart & Smarter" (season 15, 2004), where Lisa deliberately starts trying to teach Maggie incorrect answers after Maggie is erroneously claimed as being more intelligent than her (which also causes Lisa to have a dream of her and Maggie as adults where she ends up killing the latter out of an even more extreme form of jealousy than even she is really capable of), then chooses to run away from home, fearing that there is no benefit to not being the smartest Simpson; by the end of the episode, however, it is revealed that Lisa was only helping Maggie pass the tests she was given by telling her the answers from the sidelines, and the sisters are able to rekindle their close relationship without any long-lasting damage to it. A notable case of Lisa's envy occurs in "Jazzy and the Pussycats" (season 18, 2006), where Bart – whom one of the family's psychiatrists, Dr. Brentano, has had take up the drums as a way to channel his usually negative habits into something constructive following an incident with a paddleball at the funeral for Homer's "Vegas wife", Amber – upstages her and becomes a celebrity at a jazz brunch, leaving her to feel cheated and of the belief that Bart should not be famous and popular simply because of his newfound drumming skills; she then resorts to freeing animals to console herself. Similar to her academics, Lisa sees herself as the top musician in the school: despite her best efforts in persistently trying to get others interested in jazz music, she is often turned down, and while she is often welcoming of new saxophone players to the school band, she will become jealous should they demonstrate apparently better playing than hers. In "Girl's in the Band" (season 30, 2019), she is specifically singled out by Victor Kleskow, the musical director of the Capital City Philharmonic, for her talents, and, on Kleskow's initiative, becomes privileged as the only member of the school band to be enrolled in that orchestra, initially enthusiastically but with which she herself eventually becomes uneasy with.

Lisa's narcissism and self-esteem also regularly combine and lead her to deeply value her integrity, sometimes at the expense of others' needs and happiness, as shown, for example, in "Lisa Gets an 'A'", where, after recovering from a bad cold, but due to having constantly been distracted by a video game during her recovery, she cheats, with Nelson Muntz's help, on a test about the novel The Wind in the Willows to attain the school's highest-ever grade of A+++; she does, however, eventually admit her dishonesty to an unreceptive Principal Skinner – despite the fact that, as pointed out by both Skinner and the equally unreceptive Superintendent Chalmers, that grade allows the school to gain a "desperately" needed financial grant from State Comptroller Atkins – and is later seen self-grading her own test as an F at home. The season 19 finale "All About Lisa" (2008) features a more positive example of both this trait and her narcissism that is, in the latter's case, related neither to her academics nor to her musicianship: in that episode, Lisa becomes Krusty the Clown's newest assistant and steals his spotlight, going on to host her own television show and win "Entertainer of the Year" at the Springfield Media Awards before being warned that with her sudden fame comes a new attitude towards others and herself, ultimately causing her to opt to "get [back] out [of show business] while [she] still can" by calling a dejected Krusty up to the stage to regain his reputation and his show, while she herself gets to retain both her award and "her dignity". Lisa's integrity also extends to her general appearance: for example, in "Lisa the Beauty Queen" (season four, 1992), in a sacrificial move demonstrating his capability to be a caring and loving father, Homer sells his cherished ride on the Duff Beer Blimp and uses the money to enter Lisa into a beauty pageant so that she can feel better about herself after she is humiliated by a caricature artist at the school carnival. She wins second place at the pageant, but due to the winner, Amber Dempsey, coincidentally being struck by lightning the next day, Lisa becomes "Little Miss Springfield" by default, using her new platform to inundate Springfield with anti-corporate public service announcements in defiance of the role's intended purpose as being a spokesperson for Laramie Cigarettes. Additionally, at times, she seems to be self-conscious about her body, as shown in such episodes as "Lisa's Date with Density" (season eight, 1996), "Old Yeller-Belly" (season 14, 2003), "The President Wore Pearls" (season 15, 2003), "Sleeping with the Enemy" (season 16, 2004) and "Lisa's Belly" (season 33, 2021), all of which, between them, feature, at certain points, several other characters making fun of her weight and, in some cases, regarding her posterior as being very fat. Lisa's self-esteem can, however, also sometimes lead to a sense of vanity, as shown, for example, in "Bart of Darkness" (season six, 1994), where, after the Simpson house's backyard swimming pool is installed, she suddenly acquires a love of glamor, revelling in her (and, initially, Bart's) subsequently and significantly increased popularity with other residents of Springfield, and letting the other children playing there work for her while she lies in a floating chair and admires her bare feet and naked toes. Another episode to show both her integrity and her display of moral superiority at once is "Pranksta Rap" (season 16, 2005), in which Lisa, this time with Skinner's support and help, demonstrates her willing to reveal the truth to everyone in Springfield about Bart faking his own kidnapping to go to a gangsta rap concert hosted by MC Alcatraaaz, despite the fact that virtually everybody involved in the case (especially Chief Wiggum and Kirk Van Houten) has apparently become better off. There have also been other, more peculiar, instances where Lisa has been shown to use extreme measures to address her points and ideals, such as her aforementioned sabotage of Allison's diorama in "Lisa's Rival", and throwing paint on Krusty the Clown for wearing a fur coat in "G.I. (Annoyed Grunt)" (season 18, 2006) before innocently asking the latter about his latest film. The strength of Lisa's conscience and her sense of morality, however, usually prevents her from committing unethical acts generally and not punishing herself afterwards, allowing the status quo of her usually being a good girl to prevail largely unchanged.

Outside of her school studies, Lisa is shown on occasion to demonstrate her own independent learning, such as becoming fluent in the Italian language with help from Milhouse before going to Italy as part of a summer opportunity, and also showing a good understanding of French, German and Spanish (the second with the additional help of a verb wheel). Additionally, in "The Great Simpsina" (season 22, 2011), she studies under The Great Raymondo (played by guest star Martin Landau) to become a skilled magician in her own right, the titular personality of that episode.

Lisa's sexuality has become the subject of speculation amongst viewers of the show.

Lisa is shown to have heterosexual crushes on Nelson Muntz and Langdon Alger in "Lisa's Date with Density" (season eight, 1996) and "Bart on the Road" (season seven, 1996), respectively. In some episodes, Lisa is shown to have a boyfriend, such as Edmund Dracula in "Treehouse of Horror XXI" (season 22, 2010) or Colin in The Simpsons Movie (2007), although all such relationships have, to date, only been temporary. Lisa becomes engaged to, and later almost marries, Hugh Parkfield in "Lisa's Wedding" (season six, 1995), and the episode "Holidays of Future Passed" (season 23, 2011) suggests that Lisa will go on to marry Milhouse Van Houten. However, some episodes, including "Holidays of Future Passed", also show Lisa being in both a monogamous, and later polyamorous, lesbian relationships. However, all future episodes and scenes such as these are ultimately considered non-canon.

Lisa's dream crush is Corey Masterson, a teenage heartthrob and local celebrity, as first revealed briefly in "Bart's Dog Gets an 'F'" (season two, 1991) and sometimes further re-affirmed beginning in "Brother from the Same Planet" (season four, 1993), in which she is shown constantly calling "The Corey Hotline". She has also been shown to have relationships with: Jesse Grass, a vegan and radical environmentalist, in "Lisa the Tree Hugger" (season 12, 2000); Luke Stetson, a ranch hand, in "Dude, Where's My Ranch?" (season 14, 2003); Brendan Beiderbecke, a skilled fifth-grade pianist, in "Haw-Haw Land" (season 29, 2018); Thelonious, Lisa's male "doppelgänger", in "Trilogy of Error" (season 12, 2001); and Nick, a seemingly gallant boy and an apparent lover of classical literature, in "The Daughter Also Rises" (season 23, 2012). As is typical of Lisa's age, however, most of these relationships, apart from that with Corey, have often been rather simple and childlike, brief, and somewhat infrequent.

Although Lisa's sexuality has never been confirmed on screen, showrunner Al Jean said in a 2019 interview with The Metro that he had always envisaged for Lisa to grow up to become bisexual and polyamorous. In a 2020 interview with The Stryker & Klein Show on KROQ Radio, Yeardley Smith said that she believed that Lisa was "still exploring her sexuality". Smith also asked fans to stop speculating on Lisa's sexuality, as she was "ultimately an eight-year old girl". The show itself had previously alluded to this speculation in "No Loan Again, Naturally" (season 20, 2009), in which Bart humorously suggests that Lisa is "gay"; instead of rebutting that claim, she sarcastically remarks that she would "hate to be gay like [her] heroes."

Lisa has been a popular character since the show's inception. She was listed at number 11 (tied with Bart) in TV Guide's "Top 50 Greatest Cartoon Characters of All Time." She appeared in Comcast's list of TV's Most Intriguing Characters and was also included in AfterEllen.com's Top 50 Favorite Female TV Characters. On a less positive note, however, she was ranked third in AskMen's top 10 of the most irritating '90s cartoon characters. Yeardley Smith has won several awards for voicing Lisa, including a Primetime Emmy Award for "Outstanding Voice-Over Performance" in 1992 for "Lisa the Greek" (season three). Various episodes in which Lisa stars have won Emmy Awards for Outstanding Animated Program, including "Homer vs. Lisa and the 8th Commandment" (season two) in 1991, "Lisa's Wedding" (season six) in 1995 and "HOMR" (season 12) in 2001. On January 14, 2000, Lisa and the rest of the Simpson family were awarded a star on the Hollywood Walk of Fame at 7021 Hollywood Boulevard.

Lisa's environmentalism has been especially well-received. In 2001, Lisa received a special "Board of Directors Ongoing Commitment Award" at the Environmental Media Awards. "Lisa the Vegetarian" (season seven, 1995) won both an Environmental Media Award for "Best Television Episodic Comedy" and a Genesis Award for "Best Television Comedy Series, Ongoing Commitment" in 1996. Several other episodes that feature Lisa speaking out in favor of animal rights have won Genesis Awards, including "Whacking Day" (season four, 1993) in 1994, "Bart Gets an Elephant" (season five, 1994) in 1995, "Million Dollar Abie" (season 17, 2006) in 2007, and "Apocalypse Cow" (season 19, 2008) in 2009.

According to Smith, executive producer James L. Brooks chose Lisa as one of his two favorite Simpsons characters (the other being Marge), both with whom he could reportedly identify the most. Chris Turner writes in Planet Simpson that Lisa and Marge are more popular than Homer and Bart in Japan, France, Quebec and many French-speaking countries. Creator Matt Groening, showrunner Al Jean and former showrunner Mike Scully all also identify Lisa as their favorite Simpsons character, with Groening foreseeing her as "the only character who is going to grow up and escape from Springfield", Jean praising her intellectualism, and Scully's favoritism being based on having several daughters of his own. According to Brooks and Groening, on a slightly less positive note, series co-developer Sam Simon had apparently deemed Lisa and Marge to be "too goody two-shoes for his tastes", preferring Homer and Bart more for their eccentric personalities.

Rich Knight, Dave Nemetz and Erica Banas – writing for CinemaBlend, TVLine and WMMR, respectively – all regard Lisa as The Simpsons' best character (over the usually more popular Homer and Bart). Knight particularly praised Lisa's dialogue, character development, moral reasonings, future ambitions and her fans' relations with her, asserting, in contrast to one of Turner's observations, that she really is "a grown woman in a child's body". Nemetz likewise praised Lisa's "formidable" intellect and "insatiable thirst for knowledge", observing that she has also become "first in [many fans'] hearts". Banas describes Lisa as "the most human and relatable character on the show", stating that "It's easy to understand the popularity of Homer and Bart (especially taking into account their catchphrases), but Lisa deserves her due [as] an 8-year-old girl [who] is essentially [Springfield's] moral compass and their de facto social justice warrior before that lightning rod term was invented."

Barry Levitt ranked Lisa third on his 2022 list of the 50 best Simpsons characters for Looper (behind Marge in first place and Homer in second), making her the highest-ranked Simpson child on that list (ahead of Bart in seventh place and Maggie in 17th), calling her the "saxophone-playing wunderkind of the Simpson family" and observing that "Though living in the shadow of the hyperactive Bart would be difficult for any child, this middle child shines bright." Like Nemetz and Banas, Levitt furthermore praised Lisa's academic brilliance and her persistent courage to "voice her beliefs and fight for what's right", defending her various ambitions by noting that "While [some of her actions] might rub some people the wrong way, [they will] never stop her from trying [her best]."

Lisa and Yeardley Smith are both widely regarded as national treasures and, in Lisa's case, a cultural icon, alongside the rest of her family (especially including Homer and Bart). Speaking on Good Morning America in 2020, Smith called Lisa "the best parts of who [she would] like to be" and "really far more extraordinary than [Smith herself] often [felt] on a day-to-day basis", prominently emphasizing her child prodigy traits and future ambitions, and describing her as "funny and multi-faceted and complicated and flawed and aspirational." Lisa has also been noted as being a significant and positive role model for many people from all areas of society. Due to profound role association and subsequently her embrace of her own character, Smith has increasingly more commonly, and proudly, referred to Lisa as "[her] girl", despite originally not having identified with Lisa as much as she has in the years since.

Jonathan Gray, author of the book Watching The Simpsons, feels that Lisa "is probably the best and certainly longest-running feminist character that television has had. She's the heart of the show and she quite often questions gender politics." In 2001, Christopher Borrelli of The Toledo Blade wrote, "Has there ever been a female TV character as complex, intelligent, and, ahem, as emotionally well-drawn as Lisa Simpson? Meet her once and she comes off priggish and one-note – a know-it-all. Get to know her and Lisa is as well-rounded as anyone you may ever meet in the real world." More recently, Gabrielle Moss, writing for Bustle in 2014, remembered Lisa as a "crucial role model" for many female Generation Xers, calling her "an intersectional feminist" who "[recognizes] that systems of oppression all work in concert with each other" and is not afraid to partake in "questioning authority, standing up for anyone who seemed oppressed (from injured animals to female pee-wee football players), and calling out sexism wherever she [sees] it – all the while wrestling with her own internal contradictions", while, like Borrelli, also recognizing her emotional flaws. Likewise, writing for NME in 2017, Helen Thomas called Lisa "one of the greatest feminist TV characters of all time", citing her as a major influence both on herself and additionally on "thousands of other little girls of the millennial generation", and praising her overachievements, feminism and future aspirations in such "traditionally male dominated careers" as those in "science, journalism and politics".

In February 2018, Darryn King of Vanity Fair continued this general trend of praise and called Lisa "the beating heart of The Simpsons" and "a role model to a generation of women", furthermore acknowledging her, according to Matt Groening, to often be "the only character on the show not controlled by his or her base impulses". He also reported about former writer David Cohen's statement re-affirming Lisa's "[caring] and [feeling] so deeply about things", Smith's "favorite thing about Lisa Simpson [being] her resilience" and own observation that "other people look up to [Lisa] too", and additionally himself covered the parallels between Smith's and Lisa's upbringings, more specifically noting that "If Lisa Simpson has endured a disproportionate amount of suffering and strife over the years, Yeardley Smith has spent much of her life grappling with troubles of her own." On the last point, however, Smith herself considers Lisa, despite the latter's flaws, as still being much luckier than Smith herself was, noting that "Lisa Simpson is nothing if not ambitious. I didn't even get into college, so there's that. So it's sort of hilarious that Lisa Simpson is so smart. This is where we part ways, people. Academically." In a humorous addendum to her March 2024 article for Remind Magazine about "real-life wonder [women]", Lori Acken regarded Lisa as "a sunny optimist in a snarky world", referencing her charismatic personality as being a contrast to the wider satirical indifference of Springfield.

In a tongue-in-cheek article from 1994 featuring Lisa as herself, Ms. Magazine praised her encouragement of feminism, women's rights, and the crusade against objectification and stereotypes of women, identifying her as one of "The Many Faces of Feminism", stating that she "wages a one-girl revolution against cartoonland patriarchy every week on Fox TV's The Simpsons" and that "whether she's marching for gay rights, subverting Thanksgiving with a tribute to forgotten formothers, or demanding equal pay for equal work during household chores, Lisa's personal [stance] is intensely political", and briefly citing the events of the then-recently aired "Lisa vs. Malibu Stacy" (season five), in which she develops an opposition to sexist talking dolls, as a major example of her actions on that front. The magazine also reported that Simone de Beauvoir and George Eliot, among other early feminists, helped to inspire Lisa's feminism, "as did 'The off chance that [her] father, Homer, and [her] brother, Bart – much as [she loves] them – represent a fair cross-section of American men.'" The magazine's observations were later supported by both Moss and Thomas – with the former also regarding Lisa as television's "most consistent" and "most bad-ass" feminist, and additionally a major inspiration for many later feminist characters such as Rory Gilmore and Buffy Summers – and its prediction of Lisa becoming the "first straight female" to hold the office of President of the United States came true in the flashforward episode "Bart to the Future" (season 11, 2000), something that "makes total sense" to Smith.

According to PETA, Lisa was one of the first vegetarian characters on primetime television. In 2004, the organization included Lisa on its list of the "Most Animal-Friendly TV Characters of All Time". In 2008, environmentalist website The Daily Green honored Lisa's role in The Simpsons Movie with one of its inaugural "Heart of Green" awards, which "recognize those who have helped green go mainstream." They wrote that "young Lisa Simpson has inspired a generation to wear their hearts on their sleeves and get educated, and involved, about global issues, from justice to feminism and the environment." Japanese broadcasters reversed viewer dislike of the series by focusing marketing of the show on Lisa. Lisa's well-intended but ill-fated struggles to be a voice of reason and a force of good in her family and community struck a chord with Japanese audiences. Mario D'Amato, a specialist in Buddhist studies at Rollins College in Florida, described Lisa as "open-minded, reflective, ethical, and interested in improving herself in various ways, while still preserving a childlike sense of innocence. These are all excellent qualities, ones which are espoused by many Buddhist traditions."

Lisa and the rest of the Simpsons have had a significant influence on English-language idioms. The dismissive term "meh", used by Lisa and popularized by the show, entered the Collins English Dictionary in 2008. In 1996, The New York Times published an article saying that Lisa was inspiring children, especially young girls, to learn to play the saxophone, a finding Smith agrees with as being another of Lisa's many "positive impact[s]".

Lisa Simpson was mentioned at the 2018 Conservative Political Action Conference when Senator Ted Cruz called the Democratic Party "The Party of Lisa Simpson", as opposed to the Republican Party being the party of several other major characters. This was also pointed out by Smith.

"Lisa the Skeptic" (season nine, 1997) and "The Monkey Suit" (season 17, 2006) are episodes of The Simpsons that delve, from Lisa's perspective, into themes of skepticism, religion and science. These episodes demonstrate the show's commitment to encouraging critical thinking and questioning of established beliefs, while also acknowledging the complexities and challenges that arise in such discussions. Despite occasional missteps, The Simpsons, through Lisa, has provided a platform for exploring these important topics in an entertaining and thought-provoking manner.

Similarly, Roger Highfield, writing for Newsweek in 2014, called the "feisty" Lisa "a cartoon role model for rational thinking" and a "critical ingredient" of The Simpsons' mathematical sophistication, comparing her to mathematician and then-recent Fields Medal winner Maryam Mirzakhani, double Nobel Prize winner Marie Curie, paleontologist Mary Anning and astronomer Caroline Herschel. Observing how Lisa's boredom due to a lack of schooling leads her to construct a perpetual motion machine in "The PTA Disbands" (season six, 1995), how she helps to take the Springfield Isotots baseball team "to the championship with the help of statistics" in "The Boys of Bummer" (season 18, 2007), her delivery of an academic paper to Professor Frink's science conference, the "12th Annual Big Science Thing", on bullying in "Bye Bye Nerdie" (season 12, 2001), and how she sometimes uses mathematics to improve Bart's golf capabilities when needed, Highfield also observed Al Jean's taking pride in Lisa's "inspirational" intellectualism, particularly with Jean furthermore calling himself "an advocate of girls entering and flourishing in the physical sciences", and the comments of journalist Suw Charman-Anderson on Lisa's influence on the entry of women into the field of science, technology, engineering and mathematics, namely that Lisa "is a great role model, especially because, at first, she doesn't seem like one. The fact that she's a core character in the longest-running American sitcom, gives her an influence perhaps beyond that of flesh-and-blood women in science and maths."

More broadly, Lesley Cornelius, writing for Screen Rant in 2019, like Moss, recognizes Lisa to have "become a type of cartoon icon for many people seeking social justice around the world," even to the point of "taking arms for her favorite causes" due to being "forced to deal with the idiocracy of everyone else on The Simpsons", specifically highlighting Lisa's embrace of vegetarianism in "Lisa the Vegetarian", her environmentalism with regard to addressing global warming and climate change in "On a Clear Day I Can't See My Sister" (season 16, 2005) and "The Good, the Sad and the Drugly" (season 20, 2009), her "tackling [of] body image issues and eating disorders" in "Sleeping with the Enemy" (season 16, 2004), her defense of the freedom of the press and opposition to the concentration of media ownership in "Fraudcast News" (season 15, 2004), her rescue of sheltered animals in "Jazzy and the Pussycats" (season 18, 2006), her creation of a giant genetically modified tomato in "Duffless" (season four, 1993) as a potential "cure for world hunger", her ill-fated inhabitation of Springfield's oldest tree in "Lisa the Tree Hugger" (season 12, 2000) to stop the Rich Texan's loggers from cutting it down, her decision to stay true to herself at the end of "Summer of 4 Ft. 2" (season seven, 1996), and her creation of a pro-feminist talking doll in "Lisa vs. Malibu Stacy" as all being major examples of her "social justice efforts". According to Smith, The Simpsons' writers "[like to] use [Lisa] on the soapbox often, which can be really successful. She can, you know, make a political statement, she can make a human rights statement, whatever."

Ben Sherlock, writing for Screen Rant in 2020, acknowledges Lisa as being "truly an inspiring role model", stating that "There aren't many strong role models in the Simpson clan. Homer is a negligent alcoholic, Bart is an unscrupulous troublemaker, and Maggie is a gun-toting maniac with a hair trigger. But Lisa Simpson is arguably the most inspirational character on television. She's fair, open-minded, smart as a whip, and always fights for what's right." He furthermore states that "From raising global awareness of environmentalism issues to encouraging kids to take up the saxophone and other creative endeavors, Lisa has had as much of an impact on the world at large as any real person. She's fictional and animated, but she's also a role model we can all look up to," giving her feminism, her intellect, her embrace of vegetarianism in "Lisa the Vegetarian", her emotional resonance as first shown in "Moaning Lisa" (season one, 1990), her presidency as first predicted in "Bart to the Future", her skepticism about a supposed "angel" in "Lisa the Skeptic", her environmentalism, her opposition to corruption in the United States in "Mr. Lisa Goes to Washington" (season three, 1991), her commitment to believing only in the truth as demonstrated in several episodes, and her decision to stay true to herself at the end of "Summer of 4 Ft. 2" as all being reasons why "we can all look up to Lisa". Likewise, Monica West, writing for Society 19 in 2018, while admitting that "[she doesn't] think Lisa Simpson is someone we may think of when we think about fictional feminist role models" in that Lisa is "an eight-year old, fictional cartoon character with yellow spiked hair that's the same colour as her face", nevertheless considers the "strong, young" Lisa to be "one of [her] favourite fictional feminists", praising her "proactive activism", resilience, feminism, intelligence, self-esteem, talents, kindness and presidency as strong points of her being a positive feminist role model.

Rachel of Pop Talk With Rach, writing in 2024, observes that "whenever the show turns its focus to [the Simpson family's] middle child, Lisa is learning an important life lesson", such as in "Mr. Lisa Goes to Washington" with her aforementioned opposition to corruption, in "Lisa the Beauty Queen" (season four, 1992) with her vanity and "the dangers of the tobacco industry", in "Lisa vs. Malibu Stacy" with her opposition to "sexism, marketing, and corporate greed", and in "Lisa's Rival" (season six, 1994) with her struggle with her pride, "the human urge to compare herself to others" and her initial rivalry with Allison Taylor, while also acknowledging that Lisa and Allison eventually make amends at the end of the latter episode, with Allison forgiving Lisa for sabotaging her diorama and joining Lisa's group of friends. Rachel also observes Lisa as "unafraid to ask questions", as well as "[being] brave enough to address the entire town, demand explanations, and present her ideas", "[challenging] corporations, small businesses, and people in power, holding them accountable for their actions" and refusing to "tamper down or hide her intelligence and passion from others", instead "[letting] lets herself live, big and loud, without fear of retribution", and summarises Lisa's "fantastic" role model status as befitting of "Not one of the most influential animated characters. Not one of the most influential female characters. One of the most influential characters to ever be on television."

In 2013, Lady T of Bitch Flicks identified "six lessons [that] Lisa Simpson taught [her]", namely that: one should have "trust in [themselves] and [they] can achieve anything", as demonstrated in "Lisa vs. Malibu Stacy"; it is "okay to be sad", as demonstrated in "Moaning Lisa"; one should "stand up for what [one believes] in, but respect others' beliefs as well", as demonstrated in "Lisa the Vegetarian"; "there's no shame in being second", as demonstrated in "Lisa's Rival"; one should "follow [their] passions, even when [they] experience setbacks", as demonstrated in "Separate Vocations" (season three, 1992); and one, despite their opinions, should still "have fun and be silly", as demonstrated, for example, by many occasions showing her watching Krusty the Clown and The Itchy & Scratchy Show with Bart and "[laughing] just as hard at the cartoon violence", her obsession with Corey Masterson, having sleepovers such as that in "Flaming Moe's" (season three, 1991), and, "even though she's concerned about the media portrayal of women and girls, [indulging] in a princess fantasy from time to time and [twirling] around in fairy skirts". She concluded by stating that Lisa is often "not the most fun-loving character on The Simpsons, but at her core, she's still an eight-year-old girl, and a fully realized human character, despite being a cartoon."

Krista Jensen, writing for Hello Giggles in 2014, regarded Lisa as being "many things", such as being "the subject of a rather famous birthday chorus by Bart and Michael Jackson" in "Stark Raving Dad" (season three, 1991), "the maker of ice-cold gazpacho as a party's alternative to meat" in "Lisa the Vegetarian", and generally being "reasonable, sweet, eco-conscious and unashamed of being the brightest person in the room". She also acknowledged that Lisa inspired "generations" of viewers of The Simpsons to be "smart, safe, brave – and funny", and compared herself to Lisa in that she too was "a middle child nestled between a big brother and a baby sister ... for better or for worse". She furthermore stated that "as an adult female in a time where women's equality is a consistent topic of discussion, [she was] so thankful now for the subconscious messages [she] was getting from The Simpsons via the family's high-pitched voice of reason," while also pointing out that Lisa represents there being "[no] either/or situation when it comes to humor and knowledge" and praising Lisa's determination not to let Bart's needs "take priority over her own", her befriending of the school faculty and Bleeding Gums Murphy, and her crush on Nelson Muntz, "Springfield's most notorious bully", in "Lisa's Date with Density" (season eight, 1996) "when she thinks she may have feelings for him" while also "never, ever [giving] into Milhouse [Van Houten]'s unwanted fawning". Jensen also cites "The Secret War of Lisa Simpson" (season eight, 1997) and "Lisa on Ice" (season six, 1994) as providing other major examples of her ambitions and resilience – supporting Chris Turner's own observation of Lisa's occasional deviations from the norm – and furthermore herself observes that, despite being an eight-year-old girl, Lisa "knows the difference between right and wrong and admits when she muddles them", "makes [viewers] laugh through moments of sincere honesty, through the juxtaposition of her young self being more informed than the majority of Springfield" and "points out that, usually, real checks don't include exclamation points", concluding by stating that "Lisa is someone who girls can safely emulate, and that's a hard thing to find in the PG-13 cartoon world."

Sharon Kenwrick, writing for Babe in 2016, superlatively considers Lisa to be "the ultimate role model, because although she has both the desire and capacity to change the world, her strengths and talents are attainable", pointing out her relatability while also observing her personal "insecurities and doubts around her own self-image and intelligence", which "serve to highlight and reinforce the issues that she challenges", as shown, for example, in "Lisa vs. Malibu Stacy" and "Lisa the Beauty Queen". Describing Lisa as "the smart talking, musically talented, witty, anti-capitalist, philanthropic, moral, feminist and ecological apostle, which we have always had and will always need", Kenwrick also regards Lisa as a counterweight to the often-stereotypical depiction of "flawless" female television characters, stating that "The Simpsons [contests such] notions with Lisa to reassure and comfort young girls everywhere". She concludes by observing that "What makes Lisa such a fair and true feminist though is her drive for justice and true equality. She doesn't decorate herself with feminist-only banners, she advocates for LGBTUA communities, men, the disenfranchised, animals and the planet. She's a utopian emblem. In Lisa we trust."

Nathan Rohe, writing for The Odyssey Online in 2017, considers Lisa as being "a character that holds more value than most people think." Comparing her to Rick Sanchez from Rick and Morty and Aang from Avatar: The Last Airbender, Rohe observes Lisa as "[holding] a special place in [his] heart for several reasons", with "the two qualities that appeal to [him] the most" being Lisa's intellectualism and individuality, specifically pointing out that she "is an extremely smart and talented character" with a love of classic literature, science, mathematics and music, and that "she is very free spirited and independent", "[expressing] these talents proudly and [wishing] to pass on some of this knowledge to her friends and family". Giving an example for each of those given traits, he observes that Homer having a crayon removed from his brain in "HOMR" leads to a tighter and improved father-daughter relationship between him and Lisa, despite "Homer's increased intelligence [leading] to alienation, and in some cases outright hostility, by his peers", similar to Lisa, who herself then draws a graph showing "how increased intelligence leads to decreased happiness". Likewise, he observes that Lisa, in "She of Little Faith" (season 13, 2001), "[finds] a way to honor her Christian obligation while maintaining her Buddhist beliefs", referencing Richard Gere's words of encouragement that lead to Lisa's continued support of Christianity by agreement with Marge, while remaining a practicing Buddhist, at the end of that episode. Rohe furthermore states that "Lisa is a kid who does not fights for what she strongly believes in or feels is right and the fact that she does this as a child is one of her most important qualities", and that her "position as a child in the show is what really makes her endearing to audience members like [him]. A child can look at [Lisa] and be inspired to gain intellectual understanding on subject matters. A child can learn that [they] should have the kind of faith [they] want and not what others pressure [them] into having." He concludes by suggesting "characters in art ... [really] are the ones who inspire us and give us the drive to be better."

Sara David, writing for Vice in 2017, called Lisa "the conscience, sadness, and hope of America", "the child-Sibyl of our time and place", and the representative of "every ambitious, out-of-place, or caring girl in the world", acknowledging the early transformation of her character from simply a "female Bart" into "the brilliant, passionate person known and beloved across the world today" and observing her and other similar females to "hold a special relationship" in that they have "molded, mirrored, and moved each other over three decades". Endorsing Lisa's long-standing cultural influence and her endurance and legacy, Smith herself notes that "What's interesting is [that] Lisa Simpson has touched people of all ages, men and women. I'm just open and happy and I welcome all of it."

Arrow S. Morgan, writing for Collider in 2023, notes that "While her social activist tendencies sometimes put her in opposition to the rest of the [Simpson] family, it's hard [for general viewers] to truly dislike Lisa, even at her 'worst.'" Morgan also observes that Lisa "is a character whose heart is almost always in the right place, even (and especially) when she's incorrect about something", indirectly referencing the events of "Lisa vs. Malibu Stacy", "Lisa the Vegetarian" and "Apocalypse Cow" as examples of her activism, and concluding by stating that "It's easy to like a kid who wants to make the world better, and that's Lisa in a nutshell." Chris Turner shows a similar sentiment by briefly highlighting Lisa's general adorableness, in terms of both the latter's appearance and overall personality, as another major part of her endurance and legacy.

Smith herself concurs with all of these opinions, having stated that "Even though [Lisa] is [technically only] a little two-dimensional character on TV, ... most people think of her as three dimensional, as an actual living, breathing human being," that, according to Smith, being the "remarkable" key to the success of both Lisa herself specifically and The Simpsons generally.

Lisa has been included in many The Simpsons publications, toys, and other merchandise. The Lisa Book, describing Lisa's personality and attributes, was released in 2006, followed by Lisa Simpson's Guide to Geek Chic, expanding on her interests and friendships, in 2015. Other merchandise includes dolls, posters, figurines, bobblehead dolls, mugs, and clothing such as slippers, T-shirts, baseball caps, and boxer shorts. Lisa has appeared in commercials for Burger King, C.C. Lemon, Church's Chicken, Domino's Pizza, Kentucky Fried Chicken, Ramada Inn, Ritz Crackers, Subway and Butterfinger. Matt Groening would later say that the Butterfinger advertising campaign in particular, which began in 1988 while the Simpson family were still part of The Tracey Ullman Show, was a large part of the reason why Fox decided to pick up the family for their own half-hour show the following year; the campaign was, however, discontinued in 2001, much to the disappointment of Nancy Cartwright.

On April 9, 2009, the United States Postal Service unveiled a series of five 44-cent stamps featuring Lisa and the four other members of the Simpson family. They are the first characters from a television series, other than Sesame Street characters, to receive this recognition while still in production. The stamps, designed by Matt Groening, went on sale in May 2009.

Lisa has also appeared in other media relating to The Simpsons. She has appeared in each Simpsons video game, including The Simpsons Game, released in 2007, and was additionally the deuteragonist of the now-discontinued freemium licensed city-building mobile game The Simpsons: Tapped Out (in which her role was to help Homer rebuild Springfield and bring back key sought-out characters, following a meltdown at the Springfield Nuclear Power Plant brought on by Homer's own negligence). Lisa also appears as a playable character in the toys-to-life video game Lego Dimensions, released via a "Fun Pack" packaged with a Gravity Sprinter accessory in November 2015. In addition to the television series, Lisa regularly appeared in issues of Simpsons Comics, which were published from 1993 until 2018. The comics focused on the sweeter, more naïve incarnation from the early seasons. Lisa also plays a role in The Simpsons Ride, launched in 2008, at Universal Studios Florida and Hollywood.

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• Media related to Lisa Simpson at Wikimedia Commons
• Lisa Simpson on IMDb