The characters in the American animated television series SpongeBob SquarePants were created by artist, animator, and former marine biologist Stephen Hillenburg. The series chronicles the adventures of the title character and his various friends in the fictional underwater city of Bikini Bottom. Most characters are anthropomorphic sea creatures based on real-life species. Many of the characters' designs originated in an unpublished educational comic book titled The Intertidal Zone, which Hillenburg created in 1989.

SpongeBob SquarePants features the voices of Tom Kenny, Bill Fagerbakke, Rodger Bumpass, Clancy Brown, Mr. Lawrence, Jill Talley, Carolyn Lawrence, Mary Jo Catlett and Lori Alan. Most one-off and background characters are voiced by Dee Bradley Baker, Sirena Irwin, Bob Joles, Mark Fite and Thomas F. Wilson. In addition to the series' regular cast, various celebrities from a wide range of professions have voiced guest characters and recurring roles.

The show's characters have received positive critical reception and attention from celebrities. They have made frequent appearances in media outside of the television show, including a theatrical film series, many video games, and two spin-off series. The characters have also been referenced and parodied throughout popular culture. The title character SpongeBob became a merchandising icon during the height of the show's second season and has seen continued commercial popularity.

Stephen Hillenburg originally conceived early versions of the SpongeBob SquarePants characters in 1984, while he was teaching and studying marine biology at what is now the Orange County Marine Institute in Dana Point, California. During this period, Hillenburg became fascinated with animation, and wrote a comic book titled The Intertidal Zone starring various anthropomorphic forms of sea creatures, many of which would evolve into SpongeBob SquarePants characters, including "Bob the Sponge", who was the co-host of the comic and resembled an actual sea sponge as opposed to SpongeBob. In 1987, Hillenburg left the institute to pursue his dream of becoming an animator.

Patrick, Mr. Krabs, Pearl, and Squidward were the first other characters Hillenburg created for the show. Many of their characteristics were based on Hillenburg's experiences during his time at the Ocean Institute or inspired by the traits of their species. Patrick's personality embodies the nature of the starfish; according to Hillenburg, they look "dumb and slow" but are "very active and aggressive" in reality, like Patrick. Hillenburg drew inspiration from his former manager at a seafood restaurant while creating Mr. Krabs. According to him, this manager was redheaded, muscular, and a former army cook; these traits were all adapted into Krabs' character. His decision to design Pearl was influenced by his regular supervision of whale watches at the Ocean Institute, as well as by a cetacean skeleton at the institute. He drew Pearl with an oversized, almost geometric head as a reference to sperm whales having the largest brain size of any extant animal on Earth. He designed Squidward as an octopus because of the species' bulbous mantle; the octopus, he said, has "such a large bulbous head and Squidward thinks he's an intellectual, so of course he's gonna have [one]". Hillenburg drew Squidward with six tentacles because "it was really just simpler for animation to draw him with six legs instead of eight".

Several additions were made to the series' main cast before and after Hillenburg pitched the series to Nickelodeon; in his series bible, he added Sandy Cheeks, a squirrel clad in a diving suit, as a new friend of SpongeBob. Plankton and Karen were included in his bible but were not meant to make regular appearances; Plankton's voice actor Mr. Lawrence said that he "was only supposed to be in one or two episodes, but I was a writer on the show and I really liked this character". Following his first voice recording, Lawrence drafted some of his own ideas, hoping to "prove Plankton could survive as more than a one-note character". From then on, Plankton and Karen's roles in the series grew as Lawrence wrote ideas to give them more personality; notably, he decided to write Karen as Plankton's wife, rather than just his computer as was originally intended. They were both officially promoted to main cast members in the credits of the 2004 theatrical film, in which they play central roles.

Hillenburg added Mrs. Puff in response to a request by Nickelodeon that SpongeBob attend school. Nickelodeon executives initially wanted to make SpongeBob a child since their most successful cartoons at the time focused on young, school-age characters. Hillenburg stated that the network wanted SpongeBob to be like "Arnold [from Hey Arnold!] under the sea," but he told them, "No, that's not the show." As a compromise, he decided to put SpongeBob in a boat-driving school, allowing him to keep writing SpongeBob as an adult while also using the school as a main plot element. Showrunner Vincent Waller suggested that if Nickelodeon had creative control over SpongeBob, almost every episode would take place at Mrs. Puff's school, rather than at a variety of locations. The choice to make Mrs. Puff a pufferfish, who inflates into a ball when SpongeBob crashes, was made to evoke the appearance of car airbags.

SpongeBob SquarePants (voiced by Tom Kenny) is a yellow anthropomorphic sea sponge who usually wears brown short pants, a white collared shirt, and a red tie. Like real sea sponges, he can filter-feed and reproduce by budding. He lives in a pineapple house and is employed as a fry cook at a fast food restaurant called the Krusty Krab. He diligently attends Mrs. Puff's Boating School but has never passed; throughout the series, he tries his hardest on the exams but remains an unintentionally reckless boat driver. He is relentlessly optimistic and enthusiastic toward his job and his friends. SpongeBob's hobbies include catching jellyfish, blowing bubbles, playing with his best friend Patrick, and unintentionally irritating his neighbor Squidward. He first appears in "Help Wanted".

Patrick Star (voiced by Bill Fagerbakke) is a pink starfish who lives under a rock and wears flowered swim trunks. His most prominent character trait is his extremely low intelligence. He is best friends with SpongeBob and often unknowingly encourages activities that get the two into trouble. While typically unemployed throughout the series, Patrick holds various short-term jobs as the storyline of each episode requires, particularly with various stints at the Krusty Krab. He is generally slow and even-tempered but can sometimes get aggressive, much like real starfish, and occasionally performs feats of great strength.

Squidward Tentacles (voiced by Rodger Bumpass) is a turquoise Giant Pacific octopus with a large nose who works as a cashier at the Krusty Krab. He is SpongeBob's next-door neighbor with a dry, sarcastic sense of humor. His house is between SpongeBob's and Patrick's houses. He believes himself to be a talented artist and musician, but nobody else recognizes his abilities. He plays the clarinet and often paints self-portraits in different styles, which he hangs up around his moai house. Squidward frequently voices his frustration with SpongeBob, but he genuinely cares for him deep down and will occasionally stick up for him. This has been revealed in the form of sudden confessions when Squidward is in a dire situation or when SpongeBob is severely treated unfairly.

Eugene Krabs (voiced by Clancy Brown) is a red crab who lives in an anchor-shaped house with his daughter Pearl, who is a whale. He dislikes spending money but will go to great lengths to make Pearl happy. Krabs owns and operates the Krusty Krab restaurant where SpongeBob and Squidward work. He is self-content, cunning, and obsessed with the value and essence of money. He tends to worry more about his riches than about the needs of his employees. Having served in the navy, he loves sailing, whales, sea shanties, and talking like a pirate.

Sheldon Plankton (voiced by Mr. Lawrence) and Karen Plankton (voiced by Jill Talley) are the owners of the Chum Bucket, an unsuccessful restaurant located across the street from the Krusty Krab. Their business is a commercial failure because they sell mostly inedible foods made from chum. Plankton is a small planktonic copepod and the self-proclaimed archenemy of Mr. Krabs. His ultimate goal is to steal Krabs' secret formula for Krabby Patties, run the Krusty Krab out of business, and take over the oceanic world, but he never permanently succeeds, usually due to either SpongeBob and/or Krabs' efforts, his own incompetence and immaturity, or his own small size (except, temporarily, in The SpongeBob SquarePants Movie). Plankton is a skilled inventor and possesses a Napoleon complex due to his short stature. Karen is Plankton's own invention, a waterproof supercomputer who is more competent than Plankton, being the brains behind most of his evil plans to steal Krabs' secret recipe. She is married to Plankton and usually takes residence in the Chum Bucket laboratory. Karen speaks with a pronounced Midwestern American accent.

Sandy Cheeks (voiced by Carolyn Lawrence) is a squirrel from Texas who lives in an air-filled glass dome and wears a diving suit to breathe underwater. Whenever any aquatic creatures enter her home, they must wear helmets of water. Sandy works as a scientist, explorer, and inventor. She is a rodeo champion with a number of athletic interests, such as "sand-boarding" and karate. She speaks with a Southern drawl and uses typical Southern slang words and phrases.

Mrs. Puff (voiced by Mary Jo Catlett) is a paranoid pufferfish who is SpongeBob's teacher at boating school, an underwater driver's education facility where students drive boats like cars. She wears a sailor suit and her school is a lighthouse. SpongeBob is Mrs. Puff's most dedicated student and knows the answer to every question on her written and oral exams, but always panics and crashes when he actually boards a vessel. She puffs up into a ball when she is scared or injured. As a running gag, she is frequently arrested by the police, usually due to her being responsible for SpongeBob when he causes destruction around Bikini Bottom during his boating tests.

Pearl Krabs (voiced by Lori Alan) is a teenage sperm whale and Mr. Krabs' daughter. She wants to fit in with her fish peers, but finds this impossible to do because of the large size inherent to her species. She will inherit the Krusty Krab from her father when she grows older, but is still in high school and does not yet have a job at the family business. Pearl's favorite activities are working at the Bikini Bottom Mall, using her father's credit card to buy anything that is in style, and listening to pop music.

Gary the Snail (vocal effects provided by Tom Kenny) is SpongeBob's pet sea snail who lives with him in their pineapple home and vocalizes like a cat. Other snails and SpongeBob can understand and talk to him. Depicted as a level-headed character, Gary often serves as a voice of reason and a foil to SpongeBob and solves problems that his owner cannot. He has a pink shell that is impossibly spacious on the inside.

Patchy the Pirate (played by Tom Kenny) is the host of the series' special episodes. He is a live-action pirate and the president of the fictional SpongeBob fan club. He lives in an unnamed suburb of Encino, Los Angeles, and segments hosted by him are often presented in a dual narrative with the animated stories. He made a special guest star appearance on Big Time Rush in the episode "Big Time Beach Party" with Carlos Pena Jr. and Logan Henderson.

Potty the Parrot (voiced by Stephen Hillenburg in seasons 2–3, Paul Tibbitt from seasons 4–8, Mr. Lawrence from seasons 10–present) is Patchy's green pet parrot, depicted as a crudely-made puppet with googly eyes. The character's name is a reference to "Polly wants a cracker," a phrase often used for parrots to vocally mimic. Potty is obnoxious and often annoys or talks back to Patchy while he is trying to host an episode.

The French Narrator (voiced by Tom Kenny, portrayed by Dan Southworth in live-action appearances) is an oceanographer who films SpongeBob's world using a camera. He often introduces episodes from off-screen or narrates the intertitles as if the series were a nature documentary about the ocean. He has a thick French accent as a reference to the distinctive speaking style of oceanographer and filmmaker Jacques Cousteau. He is normally only heard, but physically appears three times. In "No Free Rides", after being accidentally hit by SpongeBob during a driving test, his legs, which are wearing scuba diving fins, are visible. In "Feral Friends" and "SpongeBob's Big Birthday Blowout", he is shown in live action as a hard hat diver with his face obscured by his helmet and a red beanie hat on top, referencing the beanie hat Cousteau was widely known for wearing. In "Mimic Madness", SpongeBob impersonates him by imitating his voice and wearing a beanie and beard, once again referencing Cousteau.

Mermaid Man (voiced by Ernest Borgnine as an old man and a young man in "The Bad Guy Club for Villains", Adam West as a young man in "Back to the Past") and his sidekick Barnacle Boy (voiced by Tim Conway as an old man and a young man in "The Bad Guy Club for Villains", Burt Ward as a young man in "Back to the Past") are two elderly, semi-retired superheroes who live in Shady Shoals, a retirement home, and are stars of SpongeBob and Patrick's favorite television show. Mermaid Man is a stereotypically senile senior citizen who dramatically yells "Evil!" whenever he hears the word, while Barnacle Boy is shown to be the smarter, more sensible, and more irritable of the two. Besides being able to breathe underwater and talk to sea creatures, both men can throw water balls and telepathically summon sea creatures to help them fight crime. "Mermaid Man Begins" confirms that their given first names are Ernie and Tim, referencing the first names of their respective voice actors. Aquaman artist Ramona Fradon drew the characters' comic book adventures. A series of SpongeBob SquarePants official collectors' trading cards published by Topps gives their last names as Huckler and Strangler.

Since Borgnine and Conway's deaths in 2012 and 2019, both characters have been limited to cameo appearances without dialogue, as the showrunners chose not to recast their voices.

The Flying Dutchman (voiced by Brian Doyle-Murray in the TV series, Mark Hamill in The SpongeBob Movie: Search for SquarePants) is an irritable, mischievous pirate ghost who glows green. He is named after the ghost ship of the same name. He haunts the seven seas because his unburied corpse was used as a window display. He collects souls as a Satan-like character and resides in a cavern containing Davy Jones' Locker, a literal locker stuffed with smelly socks that belong to Monkees singer Davy Jones, which within the series is analogous to Hell and occasionally mentioned as a curse word.

King Neptune (voiced by John O'Hurley in the TV series, Paul Tibbitt in "SpongeBob vs. The Patty Gadget") is a powerful, trident-wielding merman god who rules the sea, based on the Roman mythological deity of the same name. In the series, Neptune lives in a palace in Atlantis with his wife Amphitrite and son Triton. He is usually portrayed as arrogant and selfish, showing little sympathy for the sea's fish populace. Neptune has a mostly teal color scheme with a long auburn beard and hair. He wears gold wrist bands and a matching crown decorated with a scallop ornament, plus a gold belt bearing a seahorse emblem. This version was also known as Neptune XIV as seen when his portrait is shown in Squidward's briefly-redecorated room as seen in "Krusty Towers".

A different King Neptune is featured in The SpongeBob SquarePants Movie, voiced by Jeffrey Tambor. In the film, he resides near Bikini Bottom with his daughter Mindy and resembles a light green-skinned king with a robe, a shorter beard and hair, a domed crown to cover his bald spot, and powers limited to what can be exercised through his trident.

Larry the Lobster (usually voiced by Mr. Lawrence but voiced by Bill Fagerbakke for a line in "MuscleBob BuffPants" and "House Hunting") is a lobster lifeguard, bodybuilder and workout fanatic who lifts weights. He is usually seen at Goo Lagoon alongside Scooter. He first appears in "Ripped Pants" and reappears in the spinoff Kamp Koral: SpongeBob's Under Years.

Mr. Harold SquarePants (voiced by Tom Kenny) and Mrs. Margaret SquarePants (voiced by Sirena Irwin) are SpongeBob's parents, who more closely resemble round sea sponges than SpongeBob. Harold is brown with glasses and a moustache, while Margaret is dark orange. They seem to live outside of Bikini Bottom, but still take the time to visit their son on occasion. They are proud of SpongeBob but embarrassed that he still does not have a driver's license.

The Realistic Fish head (voiced by Mr. Lawrence) is an announcer and news anchor fish, resembling a cut-out of a live-action tuna. He appears in the series' opening theme. He has been given various different names throughout the series and tie-in media; it is Mister Fish in SpongeBob's Nicktoon Summer Splash, Elaine in "The Great Patty Caper", Johnny in Battle for Bikini Bottom and Battle for Bikini Bottom – Rehydrated, and "T. McTrout" in Toonz2Nite commercials for Nicktoons UK.

Perch Perkins (voiced by Dee Bradley Baker) is a perch who works as a famous field news reporter. While the Realistic Fish Head only reports on television news programs, Perch makes physical appearances reporting about events that occur. He is normally purple with a dark purple coat with a black wig and headphones, although some episodes and Nicktoons MLB show him with an orange color scheme and a red coat.

Bubble Bass (voiced by Dee Bradley Baker) is an overweight green bass that first appeared in season 1. He is a nemesis of SpongeBob and is very picky about his food. Although initially dormant after season 1, he began to appear far more frequently as a supporting character in season 9, and he has even had a notable share of episodes focused on him in both protagonist and antagonist roles, such as "Swamp Mates".

Slappy Laslo (voiced by Tom Kenny impersonating Peter Lorre) is a fish whose voice, appearance, and mannerism are modeled after Peter Lorre. After appearing in "The Big Birthday Blowout", Slappy was shown to work as a butler for Nosferatu in "Squidferatu", "Slappy Daze", and "FunBelievable". Slappy also recurred on The Patrick Star Show as a big fan of the titular show.

Old Man Jenkins (voiced by various actors from seasons 1—10 and by John Gegenhuber since season 11) is an elderly townsperson who lives at the Shady Shoals retirement home and is a common patron of the Krusty Krab. His appearance and job changed often throughout the first ten seasons. A country style banjo music usually plays whenever he appears. This music was confirmed as a theme song in the episode 'Friend or Foe' when elementary age Eugene Krabs states, "I'd know that theme song anywhere, it's Old Man Jenkins!" One of his critical appearances is in "The Sponge Who Could Fly" wherein he plays a farmer, a sailor, and finally, a human cannonball. In season 11, the series' staff decided on a finite design for Old Man Jenkins, and the actor John Gegenhuber began to consistently voice him.

The jellyfish (vocal effects by Tom Kenny) are wild animals who reside in Jellyfish Fields, a meadow in Bikini Bottom, and have a strong affinity for music. Within the series, jellyfish behave like sentient insects, squirt jelly, buzz and swarm like bees, and can sting their enemies with electric shocks that leave painful welts.

The incidentals are a large variety of characters who function as the main background characters of the show. They are all each referred as "Incidental" followed by their given model number. Their names, jobs, personalities, relationships, ages, and sometimes gender are inconsistent and tend to differ from each episode. There is currently known to be over 300 incidental characters. These characters can usually be portrayed as customers at the Krusty Krab, beachgoers at Goo Lagoon, or characters making up a large crowd or audience, although they also commonly make supporting and/or speaking roles as well.

• Angry Jack (voiced by Dee Snider) is the owner of a snail shell emporium in "Shell Shocked". He initially pretends to have an angry demeanor as a marketing stint for his store's commercials, but becomes truly infuriated when SpongeBob accidentally destroys every shell in his emporium.
• Beatrice (voiced by Betty White) is the owner of Grandma's Apron, the store where Pearl goes to work in "Mall Girl Pearl". An older woman, Beatrice convinces Pearl not to let her teenage friends make fun of her job.
• Bob Barnacle (voiced by Bob Barker) is the director of an animal rescue center where snails escaped from to find SpongeBob in "Sanctuary!" He delivers the "have your pets spayed and neutered" line Barker used to close his game show The Price Is Right.
• Bubble Buddy (voiced by Brad Abrell) is a humanoid bubble created by SpongeBob in "Bubble Buddy". His apparent inanimateness annoys other people of Bikini Bottom, but he is later revealed to be a sentient being before moving out of the town in a taxi-shaped bubble. He later returns in the season 8 episode "Bubble Buddy Returns", having been found to live in Bubbletown, a city made completely out of bubbles.
• Craig Mammalton (voiced by Dee Bradley Baker) is a seal who is popular among Goo Lagoon beachgoers for his tanned skin and golden caramel brown bones. In "Sun Bleached", he holds parties during the night that only permits those with tanned skin to enter, the highest level of which is bleached skin. He is a parody of George Hamilton.
• Cuddle E. Hugs (voiced by Jeff Garlin) is a giant, bowtie-wearing hamster from the eponymous episode who can only be seen whenever someone ingests a rotten Krabby Patty.
• DoodleBob (voiced by Paul Tibbitt) is a drawing created by SpongeBob in his image using a human pencil, which is seemingly able to animate anything it draws. He speaks through unintelligible phrases. He appears in "Frankendoodle". He returned later in "Doodle Dimension", torturing SpongeBob and Patrick in a doodling dimension. He also featured as the main villain to defeat in the Drawn to Life: SpongeBob SquarePants Edition video game. In "Captain Pipsqueak", DoodleBob made a cameo among the villains auditioning to join E.V.I.L.
• Flats the Flounder (voiced by Thomas F. Wilson) is a green flounder who had several silent cameos in various season 1) episodes before appearing as the new student at Mrs. Puff's Boating School in "The Bully". He wants to kick SpongeBob's "butt" for no apparent reason and SpongeBob takes it as if Flats wants to murder him. He also appears during the credits of The SpongeBob Movie: Sponge Out of Water
• Gene Scallop (voiced by Gene Shalit) is a food critic who critiques the Krusty Krab in "The Krusty Sponge." He negatively reviews every aspect of the restaurant except for SpongeBob. In response to Scallop's review, Mr. Krabs exploits SpongeBob's newfound popularity by theming the Krusty Krab around SpongeBob. After Mr. Krabs got arrested by the health inspector for what his Spongy Patties did to its consumers, Gene was among the members of the jury at Mr. Krabs' trial where he tells the judge that they find him guilty of all charges. He is modeled and characterized after his voice actor, a real-life book and film critic.
• Gordon (voiced by Ian McShane) is the leader of a band of Vikings who kidnap SpongeBob and Squidward in "Dear Vikings". Except for himself, all of his crewmen are named "Olaf". In "Captain Pipsqueak", Gordon made a cameo among the villains auditioning to join E.V.I.L.
• Granny (voiced by Amy Poehler) is an elderly fish who appears in "Have You Seen This Snail?". She finds snails and force-feeds them so that she can eat them and lock their shells in a closet. She adopts Gary, who was lost in an alley, as her latest victim, but he manages to escape.
• Jack Kahuna Laguna (voiced by Johnny Depp) is a legendary human-like surfer who appears in "SpongeBob SquarePants vs. The Big One". He teaches SpongeBob and his friends how to surf so they can go back home and fend off from a legendary tidal wave known as the Big One.
• Jim (voiced by Patton Oswalt) is the Krusty Krab's original fry cook, as revealed in "The Original Fry Cook". His cooking is legendary throughout Bikini Bottom, and he is shown to be an even better chef than SpongeBob. Jim left the Krusty Krab after Mr. Krabs declined to provide him with a higher salary.
• Kenny the Cat (voiced by Biz Markie) is a gray tomcat from the eponymous episode who claims he can hold his breath underwater. He is idolized by SpongeBob until it is realized that Kenny requires an oxygen tank to breathe. After the ruse was exposed by Sandy, SpongeBob got him to continue his goals by putting him in one of Sandy's diving suits.
• Lord Royal Highness (voiced by David Bowie), also referred to as LRH, is the king of Atlantis in "SpongeBob's Atlantis SquarePantis". He invites SpongeBob and his friends for a visit to Atlantis after they find the lost piece of the coin, but eventually regrets it since they (especially Patrick) end up popping the longest living bubble accidentally with a camera flash.
• Madame Hagfish (voiced by Kristen Wiig in "The Curse of the Hex", Jill Talley in "Terror at 20,000 Leagues" and "Captain Pipsqueak") is a fish and an expert witch. In "Captain Pipsqueak", Madame Hagfish is among the villains auditioning to join E.V.I.L. In The Patrick Star Show episode "Terror at 20,000 Leagues", Madame Hagfish runs a Were-Hair Botique that tends to the underwater versions of werewolves.
• Master Udon (voiced by Pat Morita) is an old karate master who appears in "Karate Island." He is actually a scammer who wants people to invest in his condominium project, disguising it as the "King of Karate" crowning that he presents to SpongeBob.
• Nicholas Withers (voiced by Alton Brown) is the presenter of the popular lifestyle television show, House Fancy. He is pending on an award for Best Architecture during the episode that features Squilliam's house; he eventually gives it to Squidward due to the "creative" design of his ruined house.
• Queen Amphitrite (voiced by Victoria Beckham) is King Neptune's wife and Triton's mother. She is worried by her son's attitude of not wanting to inherit the throne.
• Prince Triton (voiced by Sebastian Bach) is the teenage son of King Neptune who appears in "The Clash of Triton". He initially wants to be a normal fish like everyone else, but his father convinces him otherwise.
• Sal (voiced by Gilbert Gottfried) is the proprietor of the Slop Pail restaurant seen in "The Hankering". Mr. Krabs frequents the establishment until Sal decides to close it down permanently so he can pursue an acting career.
• Santa Claus makes several appearances throughout the series, portrayed in live-action form by series writer Michael Patrick Bell in "Christmas Who?", then in claymation by John Goodman for "It's a SpongeBob Christmas!". Lewis Black took over the role for later seasons, with Santa appearing traditionally animated and for a Kamp Koral episode in CGI. The Lewis Black version is generally annoyed by SpongeBob's antics, referring to him as "a menace" in a non-spiteful kind of way.
• The Sea Bear (vocal effects provided by Dee Bradley Baker) is a creature that appears in "The Camping Episode". It is depicted as a giant fish with the head of a bear and claws on its fins. SpongeBob and Patrick try to convince Squidward that the Sea Bear exists, but Squidward refuses to believe in the creature until it attacks him repeatedly when he did things that attract a Sea Bear like playing his clarinet badly, wearing a sombrero in a goofy fashion, stomping on the ground (Sea Bears take that as a challenge), waving around a flashlight (flashlights are its natural prey), eating cubed and sliced cheese, and screeching like a chimpanzee. Sea Bears also hate it when someone runs, limps, or crawls away from it. Only an Anti-Sea Bear circle can repel a sea-bear. On a related note, the sound of a Sea Bear attack can attract a Sea Rhinoceros.
• Sea Monster (voiced by Gene Simmons) is a lizard-like sea monster who appears in "20,000 Patties Under the Sea". After having slept for 79 years, he demands for SpongeBob and Patrick to sell him food in exchange for giant dollar bills.
• Sergeant Sam Roderick (voiced by Robin Sachs) is a strict drill sergeant shark who temporarily replaces Mrs. Puff as the teacher at boating school in "Mrs. Puff, You're Fired". He is said to be the strictest driving instructor in the sea, but even he cannot teach SpongeBob to drive successfully.
• Sharkface (voiced by Henry Winkler), Lonnie (voiced by Michael McKean), Ronnie (voiced by Clancy Brown) and Donnie (voiced by David Lander) are a street gang of sharks who appear in the episode "Sharks vs. Pods", in which SpongeBob joins them. They are actually dancers rather than fighters and are rivals to Squidward's gang, a group of octopuses called the Pods.
• Spot is Plankton's pet amoeba, who lives in the Chum Bucket with him and Karen. Spot behaves similarly to a puppy, is a good retriever, and can grow very large when he needs to protect his owner. He first appears in the season 9 episode "Plankton's Pet," and reappears in several episodes from season 11 onward.
• Squilliam Fancyson III (voiced by Dee Bradley Baker) is an octopus and Squidward Tentacles' arrogant, wealthy arch-rival, who has succeeded in everything Squidward had aspired to. He owns a four-story mansion with an expansive garden on the rooftop. He appears in six episodes throughout the first seven seasons, most notably in "Band Geeks" where Squidward finally emerges victorious against him by leading an unexpectedly successful band performance. Alternate versions of him appear in "Back to the Past" and "Code Yellow", but he has not made a physical appearance since "Keep Bikini Bottom Beautiful".
• Sticky Fins Whiting (voiced by Joe Pantoliano in "The Getaway" and "End of Summer Daze", Tom Kenny in "Captain Pipsqueak") is a prisoner who escapes from Bikini Bottom Prison in "The Getaway" and mistakes SpongeBob as his getaway driver which makes things worse for him. In "Captain Pipsqueak", Sticky Fins Whiting is among the villains auditioning to join E.V.I.L. In the Kamp Koral: SpongeBob's Under Years episode "End of Summer Daze", Whiting and Dorsal Dan show up at Kamp Koral where they end up hiding the loot they've stole in the pies that were made. Both of them were chased away by the jellyfish.
  • Dorsal Dan (voiced by Steve Buscemi in "The Getaway", Clancy Brown in "The Krusty Slammer", Rodger Bumpass in "Captain Pipsqueak") is a fish who was supposed to be Sticky Fins Whiting's getaway driver only for a mix-up involving SpongeBob to occur. In "Captain Pipsqueak", Dorsal Dan is among the villains auditioning to join E.V.I.L. In the Kamp Koral: SpongeBob's Under Years episode "End of Summer Daze", Dorsal Dan and Sticky Fins Whiting sho up at Kamp Koral where they end up hiding the loot they stole in the pies that were made. Both of them were chased away by the jellyfish.
• The Tattletale Strangler (voiced by Thomas F. Wilson) is a criminal fish who appears in "SpongeBob Meets the Strangler". He is detained for repeatedly strangling someone and promises to strangle SpongeBob when the latter has him arrested. He escapes from jail and pretends to be a bodyguard to get close to SpongeBob, but SpongeBob's behavior annoys him to the point where he would rather be back in prison. In "Captain Pipsqueak", the Tattletale Strangler" made a cameo among the villains auditioning to join E.V.I.L.
• The Warden (voiced by R. Lee Ermey) is the head prison warden of the Inferno Island prison, appearing in "The Inmates of Summer". His demeanor is a stereotype of a drill sergeant: strict, demanding, and always speaking in a loud tone. This portrayal is reminiscent of Ermey's performance as Gunnery Sergeant Hartman in Stanley Kubrick's Full Metal Jacket.

In Mermaid Man and Barnacle Boy's show within a show and real-life, Mermaid Man and Barnacle Boy have fought an assortment of villains where some of them have encountered SpongeBob SquarePants and Patrick Star before. Some of them are shown to be members of the B.G.A.T.F.B.C. (short for Bad Guys All Together for Book Club) in "The Bad Guy Club for Villains.

• Atomic Flounder (voiced by Carlos Alazraqui in "Mermaid Man and Barnacle Boy II", Dee Bradley Baker in "The Bad Guy Club for Villains" is an irradiated flounder and one of the enemies of Mermaid Man and Barnacle Boy. In his youth, Atomic Flounder wore a hazmat suit. He was shown to have retired from crime. In "The Bad Guy Club for Villains", Atomic Flounder was redesigned where he now resembles a humanoid mutant flounder with an arm growing from his left arm and an eye growing from the right side of his eye. He was shown to be associated with the B.G.A.T.F.B.C.
• Dirty Bubble (voiced by Charles Nelson Reilly in his first appearance, Tom Kenny in later appearances) is a villain against Mermaid Man and Barnacle Boy. He is a giant brown bubble with a face that is vulnerable to pointy items. The Dirty Bubble was one of the founders of the evil organization E.V.I.L. (short for Every Villain is Lemons) in "Mermaid Man and Barnacle Boy IV" and was part of the group again in "Captain Pipsqueak". He is also shown to be a member of the B.G.A.T.F.B.C.
• Kelp Thing (voiced by Tom Kenny) is a kelp-themed supervillain who is an enemy of Mermaid Man and Barnacle Boy.
• Man Ray (voiced by John Rhys-Davies in the first appearance, Bob Joles in later appearances) is a villain against Mermaid Man and Barnacle Boy. Man Ray has a man's body and a helmet shaped to look like a manta ray's head, which hides the fact that he does not have a head. He is a spoof of Aquaman's arch enemy, Black Manta. Though Man Ray retires as a supervillain in his first appearance, he later goes back to being a villain where he even became a founder of E.V.I.L. (short for Every Villain is Lemons) in "Mermaid Man and Barnacle Boy IV" and was part of the group again in "Captain Pipsqueak".
• The Moth (voiced by Mark Hamill) is a supervillain moth and an enemy of Mermaid Man and Barnacle Boy who appears in "Night Light". Even though he is minuscule, he has the strength to carry both SpongeBob's house and a lighthouse.
• Robot Mantis (vocal effects provided by Tom Kenny) is a robotic mantis that Mermaid Man and Barnacle Boy fought in the theme song seen in "The Bad Guy Club for Villains". In "Captain Pipsqueak", the Robot Mantis is among those that auditioned to join E.V.I.L. only to be destroyed by Man Ray because the piano belonging to Gramma that he turned into different instruments was just tuned.
• Sinister Slug (voiced by Mr. Lawrence) is a gray sea slug and an enemy of Mermaid Man and Barnacle Boy who can climb walls and shoot slime. He was shown to resemble a green sea slug in a green mask and outfit in "Mermaid Man and Barnacle Boy II". In "The Bad Guy Club for Villains", Sinister Slug was redesigned with a more realistic biege body, sharp teeth, and red eyes where he was shown to be a member of B.G.A.T.F.B.C.
• Jumbo Shrimp (voiced by Dee Bradley Baker) is a large muscular shrimp with super-strength who is an enemy of Mermaid Man and Barnacle Boy. He resembles a muscular pink shrimp in "Mermaid Man and Barnacle Boy II". In "The Bad Guy Club for Villains", Jumbo Shrimp was redesigned where he resembles a real shrimp with spiky antennae, muscular arms, four legs, and a long tail. He was also shown to be a member of B.G.A.T.F.B.C.

The International Justice League of Super Acquaintances (or IJLSA for short) are a group of the ocean's greatest superheroes that Mermaid Man and Barnacle Boy are associated with. An earlier version of the group was called the International Justice Lodge of Super Acquaintances as seen in "The Bad Guy Club for Villains".

In "Mermaid Man and Barnacle Boy IV", SpongeBob and his friends had to pose as some of its members to help Mermaid Man fight E.V.I.L. In "The Bad Guy Club for Villains", it was shown that Mermaid Man and Barnacle Boy's enemies were not familiar with them at first.

• Quickster - A superhero and member of the IJLSA with super-speed. SpongeBob SquarePants once operated as him.
• Captain Magma - A superhero with a volcano on his head and member of the IJLSA that can shoot lava when "Krakatoa" is shouted. Squidward Tentacles once operated as him.
• Professor Magma (vocal effects provided by Tom Kenny) - A magma-themed superhero and member of the IJLSA that was seen in "The Bad Guy Club for Villains".
• Elastic Waistband (voiced by Dee Bradley Baker) - An elastic superhero and member of the IJLSA. In "Mermaid Man and Barnacle Boy IV", Elastic Waistband is shown to have elasticity where Patrick Star once operated as him. In "The Bad Guy Club for Villains", Elastic Waistband was redesigned where his torso can inflate to ball shape when he unbuckles his waistband.
• Miss Appear (voiced by Sirena Irwin) is a superhero with invisibility and member of the IJLSA. In "The Bad Guy Club for Villains", Miss Appear was redesigned to resemble a parody of Wonder Woman.
• Pyrite Ponderer (voiced by Tom Kenny) is a pyrite-themed superhero and member of the IJLSA who wields the Hairnet of Knowledge that can do other things. He is known for giving advice and making comments like "Do we really exist" and "violence resolves nothing".

• Princess Mindy (voiced by Scarlett Johansson) is King Neptune's daughter. She is Patrick's love interest. She is a motherly and friendly person and a very good friend of SpongeBob and Patrick. She appears in The SpongeBob SquarePants Movie. She isn't mentioned in the TV series, but does appear in the special "SpongeBob's Big Birthday Blowout".
• Dennis (voiced by Alec Baldwin in the film, Clancy Brown in the TV series) is a hitman hired by Plankton to assassinate SpongeBob and Patrick before they are able to retrieve King Neptune's crown from Shell City. Before he manages to do that however he is first stomped by the Cyclops and then hit by a pier. He only appeared in The SpongeBob SquarePants Movie and made a speaking cameo in "Captain Pipsqueak" where he was the receptionist for E.V.I.L.
• The Cyclops (performed by Aaron Hendry, vocal effects provided by Neil Ross) is a marine diver who is always seen wearing an atmospheric diving suit and helmet, even when not underwater, and never talks but only grunts appearing only in The SpongeBob SquarePants Movie. He is actually a normal adult man; however, because humans tower virtually all sea life, Mindy describes him as "the worst of all hazards". He is the owner of "Shell City", which is really the name of a seaside gift and souvenir shop.
• Burger-Beard the Pirate (portrayed by Antonio Banderas) is a pirate who, upon discovering a book capable of rewriting reality, steals the Krabby Patty formula to open up a fast food drive-in while also changing Bikini Bottom into a wasteland. He appears in The SpongeBob Movie: Sponge Out of Water.
• Kyle (voiced by Paul Tibbitt (US)/Joe Sugg (UK)/Robert Irwin (Australia)) is an innocent seagull that listens to the stories of Burger-Beard. He appears in The SpongeBob Movie: Sponge Out of Water.
• Bubbles (voiced by Matt Berry in the film, Jeff Bennett in the video game) is a god-like bottlenose dolphin who is the overseer of the universe, watching them from a triangular building in outer space. SpongeBob and Plankton accidentally end up in his audience while using Karen's time machine in The SpongeBob Movie: Sponge Out of Water.
• King Poseidon (voiced by Matt Berry) is the ruler of the seven seas who resides in Atlantic City and is much different from King Neptune. He uses snails' slime as face cream to look younger, which is the reason he kidnapped SpongeBob's pet snail Gary once he was all out of snails. He only appeared in The SpongeBob Movie: Sponge on the Run.
• Chancellor (voiced by Reggie Watts) is King Poseidon's assistant. He appears in The SpongeBob Movie: Sponge on the Run.
• Sage (portrayed by Keanu Reeves) is a tumbleweed with a human face who helps SpongeBob on his quest to save Gary. He appears in The SpongeBob Movie: Sponge on the Run.
• El Diablo (portrayed by Danny Trejo) is the leader of vampire cowboy zombies whom SpongeBob and Patrick encountered in their dream. He appears in The SpongeBob Movie: Sponge on the Run.

• Nobby and Narlene (voiced by Carlos Alazraqui and Kate Higgins) are characters in the spin-off series Kamp Koral: SpongeBob's Under Years. They are a pair of hillbilly narwhals who live in the Kelp Forest. The narwhal siblings have crossed over into the main series on different occasions: the episodes "Something Narwhal This Way Comes", "Upturn Girls", "Sandy, Help Us!" and "In the Mood to Feud". In the main series, Nobby is shown to be larger and muscular while Narlene was just taller.
• The Kraken (voiced by Brad Garrett impersonating Rodney Dangerfield) is a sea monster in Kamp Koral: SpongeBob's Under Years that was seen living in the lake at Kamp Koral where he is shown to have a comedic side. He later crossed over into the main series where he appeared at the end of "Abandon Twits".
• Cecil Star (voiced by Thomas F. Wilson) and Bunny Star (voiced by Cree Summer) are Patrick's parents in the spin-off series The Patrick Star Show. Cecil works at the Undersea Space Center while Bunny works from home. Cecil later appeared in the Kamp Koral: SpongeBob's Under Years episode "Help Not Wanted" where he visits his son and was revealed to have been a former camper at Kamp Koral as well as made cameos in the main series.
• Squidina Star (voiced by Jill Talley) is a purple squid. She was first introduced in "Goons on the Moon" as a teenage friend of Pearl. In the spin-off The Patrick Star Show, she is Patrick's adopted sister and the producer of Patrick's imaginary talk show.
• GrandPat Star (voiced by Dana Snyder) is Patrick's grandfather and Cecil's father in The Patrick Star Show. He is the smartest member of the Star family.
• Ouchie (vocal effects provided by Tom Kenny) is a sea urchin who is the Star family's pet.
• Tinkle (vocal effects provided by Dee Bradley Baker) is a sentient toilet.
• Pinkeye (vocal effects provided by Jill Talley) is a sea bunny. While often shown to be feuding with Ouchie, they get along well when they are with Tinkle.

• Blackjack SquarePants (voiced by John DiMaggio) is SpongeBob's cousin who bullied him during their childhoods. In his lone appearance, Blackjack was imprisoned for littering but has since been released. While he appeared large in flashbacks, Blackjack somehow shrunk by the present day.
• Stanley SquarePants (voiced by Christopher Guest) is SpongeBob's cousin who appears solely in the episode "Stanley S. SquarePants". SpongeBob receives Stanley in a package sent by his Uncle Clem, who is relieved to have sent Stanley, since he would destroy anything he touches. True to this, despite SpongeBob trying to teach him, Stanley constantly destroys everything and almost makes SpongeBob lose his job until SpongeBob told the truth to Mr. Krabs. This leads to Mr. Krabs hooking Stanley up with Plankton where he accidentally wrecks The Chum Bucket.
• Captain Blue SquarePants (voiced by Garnett Sailor) is SpongeBob's uncle who only appears in the episode "BlackJack". He is a retired police captain and lives right next to SpongeBob's cousin BlackJack. In the episode, SpongeBob goes to his house to help him stop BlackJack from torturing SpongeBob's parents. However, he can't hear over the lawnmower and thinks SpongeBob wants to help him mow the lawn. It goes on like this for other noisy objects such as a blender, a radio with static, and a phonograph. When he finally hears the news, he drives SpongeBob over to BlackJack's house, but he warns SpongeBob to be careful.
• Grandma SquarePants (voiced by Marion Ross) is SpongeBob's paternal grandmother. She spoils SpongeBob whenever he visits her house with cookies, milk, sweaters, and bedtime stories, even though it can embarrass SpongeBob.
• Herb and Margie Star are Patrick's parents in the original series. Their identities are temporarily taken by another starfish couple named Marty and Janet in "I'm with Stupid". In "Rule of Dumb", it is revealed that Herb is a brother of Gary's father, Sluggo, making Patrick and Gary first cousins. The characters were later dropped when Cecil Star and Bunny Star were created.
• Mrs. Tentacles (voiced by Rodger Bumpass in most appearances, Dee Bradley Baker in "Fools in April") is Squidward's elderly mother. In earlier episodes, she only appears as hallucinations tormenting Squidward, but later appears in person in "Krusty Towers". She lives in a moai like Squidward, but with a curly hair-like structure on its roof and earring-like balls hanging from the sides.
• Jeff Tentacles (voiced by Tom Kenny) is Squidward's father who was mentioned a lot before appearing in "Kamp Kow".
• Grandma Tentacles (voiced by Mary Jo Catlett in "Chum Fricasse", Cree Summer in The Patrick Star Show) is Squidward's paternal grandmother. She was originally mentioned in "Sandy's Rocket" before appearing in person in "Chum Fricasse" where Mr. Krabs tipped her off about Squidward and Plankton misusing her famous chum fricasse recipe by not letting it cook for 24 hours and had the customers wreck the Chum Bucket in retaliation. In The Patrick Star Show, Grandma Tentacles is shown to be the Star family's neighbor where she would be annoyed with their shenanigans.
• "Mama" Krabs (voiced by Paul Tibbitt in season 2–3, Sirena Irwin in season 4–6) is Mr. Krabs' overbearing mother who still treats him slightly like a child. She is a friend of Old Man Jenkins. She first appears in "Sailor Mouth" and has been mostly retired from the show, aside from a cameo in "Lame and Fortune." Although her name it is not officially mentioned in the series, she is referred to as "Betsy" in some merchandising.
• Grandpa Redbeard (voiced by Dennis Quaid) is Mr. Krabs' paternal grandfather who is a pirate. In "Grandpappy the Pirate", he visits his grandson, thinking that the latter is also a pirate instead of the owner of a restaurant. Mr. Krabs tries not to disappoint Redbeard by disguising the Krusty Krab as a pirate ship, pretending Pearl is a sea monster, and dressing his employees as sailors.
• Gordon Plankton (voiced by Clancy Brown) is Plankton's hillbilly father. In "Blood is Thicker than Grease and Oil", Gordon leads his family in opening a potato restaurant next to Plankton after winning the lottery. It doesn't last long when Plankton joined the business after failing to ruin it and placing chum in the potatoes. In "In the Mood to Feud", it is revealed that Gordon's hillbilly family has feuded with Nobby and Narlene's family over the field of bumble jellies (a bumblebee version of jellyfish) in between their properties in Bikini Holler.
• Ma Plankton (voiced by Kate Higgins) is Plankton's hillbilly mother.
• Grand Dad Plankton (voiced by Paul Tibbitt) is the father of Gordon Plankton and the grandfather of Plankton.
• Granny Plankton (voiced by Laraine Newman) is Plankton's grandmother.
• Clem Plankton (voiced by Dee Bradley Baker in "Plankton's Army", Bill Fagerbakke in "Plankton's Robotic Revenge", Carlos Alazraqui in "Something Narwhal This Way Comes", Tom Kenny in "In the Mood to Feud") is Plankton's cousin and the leader of the rest of Plankton's cousins.
• Plankton's Cousins (variously voiced by Carlos Alazraqui, Dee Bradley Baker, Clancy Brown, Rodger Bumpass, Bill Fagerbakke, Tom Kenny, Carolyn Lawrence, and Jill Talley) are the rest of Plankton's hillbilly cousins where most of them aren't named.
• Pa Narwhal (voiced by Tom Kenny) is the father of Nobby and Narlene and the patriarch of their hillbilly narwhal family. The episode "In the Mood to Feud" revealed that Pa Narwhal's family have been feuding with Plankton's family over the field of bumble jellies in between their properties in Bikini Holler.
• Ma Narwhal (voiced by Jill Talley) is the mother of Nobby and Narlene and the matriarch of their hillbilly narwhal family.
• WillyBob (voiced by Tom Kenny) is the cousin of Nobby and Narlene who appears in the main series episode "Something Narwhal This Way Comes".
• Hatty McDoody (voiced by Jack McBrayer) is the cousin of Nobby and Narlene who appears in two episodes of "Kamp Koral: SpongeBob's Under Years".

• Primitive Sponge and Primitive Star (voiced by Tom Kenny and Bill Fagerbakke) are the earliest known ancestors of SpongeBob and Patrick, who appear in the episode "SB-129" when Squidward time-travels to the past. Upon seeing the two of them electrocuting themselves with a jellyfish, Squidward inadvertently teaches them the sport of Jellyfishing, which results in Squidward being documented as the inventor of Jellyfishing when he returns to the present. They also seem to strongly dislike Squidward's clarinet music, as they ruthlessly chase down Squidward upon hearing it. The scene where Primitive Sponge and Primitive Star are confronted by Squidward upon noticing them torturing themselves with the jellyfish, particularly, the pose struck by Primitive Sponge, has become an internet meme, referred to as "SpongeGar" (which was actually the name given to another of SpongeBob's primitive ancestors in the episode "Ugh").
• SpongeGar, Patar, and Squog (voiced by Tom Kenny, Bill Fagerbakke, and Rodger Bumpass) are SpongeBob, Patrick, and Squidward's neolithic ancestors who appear in "Ugh." While still not being able to speak intelligibly, they are more advanced than the primitive ancestors in "SB-129" as they are shown to use stone tools and fire. Also appearing in the episode are Primitive Gary (voiced by Tom Kenny), Gary's gigantic ancestor and SpongeGar's pet, and Primitive Krabs (voiced by Clancy Brown), Mr. Krabs' tiny ancestor who repeatedly chants "money."
• SpongeTron and Patron (voiced by Tom Kenny and Bill Fagerbakke) are SpongeBob and Patrick's robotic descendants who appear in "SB-129". SpongeTron has 486 clones, each one named after a letter of the English alphabet from 2,000 years in the future, while Patron has two heads.
• SpongeBuck SquarePants, Pecos Patrick, Hopalong Tentacles, William Krabs, Polene Puff, and Dead Eye Plankton (voiced by Tom Kenny, Bill Fagerbakke, Rodger Bumpass, Clancy Brown, Mary Jo Catlett, and Mr. Lawrence) are the main characters' wild west ancestors who appear in "Pest of the West". They lived in the town of Bikini Gulch and frequented an old-fashioned bar version of the Krusty Krab called the Krusty Kantina.
• Squidly Tentacles, King Krabs, Princess Pearl, Dark Knight, Planktonamor, and Karen the Crystal Ball (voiced by Rodger Bumpass, Clancy Brown, Lori Alan, Carolyn Lawrence, Mr. Lawrence, and Jill Talley) are the medieval counterparts of the main characters who appear in "Dunces and Dragons". The present-day SpongeBob and Patrick are magically transported to their times and help save Princess Pearl from Planktonamor. Planktonamor additionally keeps a pet, the Dragon Jellyfish, who is a giant jellyfish with a mane and a tail.

The characters of SpongeBob SquarePants have been well-received overall. The titular character SpongeBob has become very popular with children and adults. The character's popularity has spread from Nickelodeon's original demographic of two- to eleven-year-olds, to teenagers and adults. The popularity of SpongeBob translated well into sales figures. In 2002, SpongeBob SquarePants dolls sold at a rate of 75,000 per week, which was faster than Tickle Me Elmo dolls were selling at the time. SpongeBob has gained popularity in Japan, specifically with Japanese women. Nickelodeon's parent company Viacom purposefully targeted marketing at women in the country as a method of building the SpongeBob SquarePants brand. Skeptics initially doubted that SpongeBob could be popular in Japan as the character's design is very different from already popular designs for Hello Kitty and Pikachu. However, the characters have also attracted some negative reception, including SpongeBob himself, who was listed as number four on AskMen's Top 10: Irritating '90s Cartoon Characters. Nevertheless, SpongeBob SquarePants was ranked ninth on TV Guide's top 50 cartoon characters.

The show's characters have received recognition from celebrities and well-known figures in media. Barack Obama named SpongeBob his favorite television character in 2007 and admitted that SpongeBob SquarePants was "the show I watch with my daughters." British Prime Minister Gordon Brown has also said he watches the show with his children. Sigourney Weaver and Bruce Willis were reported to be fans of the SpongeBob character in 2008. Film critic A. O. Scott named Squidward, Mrs. Puff, and Sandy his favorite characters on the show in 2004. American singer Pharrell Williams, who says he is a fan of the show, said that "Squidward is my favorite, though. If he was a human, I would hang out with him." Fashion designer Peter Jensen designed a line of sweatshirts inspired by SpongeBob and called Mrs. Puff his "absolute favorite" character in an interview with Women's Wear Daily. Peter Keepnews of The New York Times commended Patrick, calling him "a popular character, and the new episodes illustrate why: He is unfailingly enthusiastic, touchingly loyal and absolutely undeterred by his intellectual limitations. Hilariously voiced by Bill Fagerbakke, he is not just an endearing comic creation but a role model for idiots everywhere."

The show's voice actors have received attention from honorary organizations for the portrayals of their characters. Mary Jo Catlett and Tom Kenny were both nominated at the 29th Annie Awards ceremony in 2001 for their vocal performances as Mrs. Puff and SpongeBob. Kenny received an additional two nominations at the 2008 and 2010 ceremonies, the latter of which he won for voicing SpongeBob in "Truth or Square". In 2012, Rodger Bumpass' performance as Squidward was nominated for Outstanding Performer in an Animated Program at the 39th Daytime Emmy Awards. Additionally, Patrick as a character won in the category "Favorite Animated Animal Sidekick" at the 2014 Kids' Choice Awards.

The characters of SpongeBob SquarePants appeared in the 2004 theatrical film The SpongeBob SquarePants Movie and its 2015 sequel. Both films feature the regular television cast and blend animated elements with live-action sequences. They have also been featured in a variety of associated merchandise, particularly video games; from 2001 to 2013, the SpongeBob franchise had multiple video games released each year, with the show's voice cast reprising their character roles for many titles. Every main cast member with the exception of Clancy Brown has voiced their respective characters in each game that they appear; Brown's character Mr. Krabs is instead voiced by Joe Whyte in SuperSponge, Operation Krabby Patty, and Battle for Bikini Bottom and by Bob Joles in the Truth or Square game.

The SpongeBob characters have been featured at a variety of theme park attractions. In 2003, Kings Island announced plans to build the first SpongeBob-themed amusement park ride, a dark ride roller coaster titled "Mrs. Puff's Crash Course Boating School". Plans were halted when Kings Island changed ownership, and the first ride featuring SpongeBob theming was instead "SpongeBob's Boatmobiles"—also based on Mrs. Puff's Boating School and opened in 2003—at California's Great America. Amusement rides based on the characters have since been opened at Blackpool Pleasure Beach, Dreamworld, Movie Park Germany, and Nickelodeon Universe. Two 4D films featuring 3-D models of the characters and a motion simulator experience, SpongeBob SquarePants 4-D and The Great Jelly Rescue, were sold to theme parks and aquariums worldwide in 2005 and 2013 respectively.

Mascot costumes of the SpongeBob characters debuted at Nickelodeon Suites Resort in 2005 and have made regular appearances at Nickelodeon events since. Plankton, Karen, and Gary are the only main characters who have never been realized as mascots; at events, they are normally depicted as puppets or statues instead. In December 2011, a parade of SpongeBob mascots and floats titled "SpongeBob ParadePants" opened at Sea World Australia. In November 2017, a Broadway musical based on the show began previews at the Palace Theatre, and opened in December 2017. Unlike previous shows, the characters were not represented with mascot costumes but by actors wearing clothing inspired by the characters' designs.

The characters of SpongeBob SquarePants have appeared throughout popular culture. In 2007, the Amsterdam-based company Boom Chicago created a SpongeBob parody called "SpongeBob SquarePants in China", in which a stereotypically Chinese Patrick refuses to go to work and advocates freedom of speech, rights of leisure, and income. During the same year, production company Camp Chaos created a SpongeBob parody titled SpongeBong HempPants, which features five of the series' characters parodied in the form of various drugs. The show was seen on VH1 and Comedy Central, both owned by Nickelodeon's parent company Viacom. Comedy Central's Drawn Together also features a parody of SpongeBob named "Wooldoor Sockbat" whose theme tune is inspired by SpongeBob's Hawaiian-style background music. Two animated series that former SpongeBob writer Dan Povenmire worked on have incorporated references to the characters; the Phineas and Ferb special "Summer Belongs to You" features a joke in which Phineas Flynn holds up inanimate representations of SpongeBob and Patrick, and the Family Guy episode "Road to Rupert" includes SpongeBob's "Campfire Song Song" from "The Camping Episode". SpongeBob, Patrick, Mr. Krabs, Pearl and Squidward all appear in "Major League of Extraordinary Gentlemen", an episode of the sketch comedy Robot Chicken. A segment of the episode, animated in stop motion with SpongeBob toy figures, features Mr. Krabs using crab legs as the secret ingredient for Krabby Patties. In April 2016, Nintendo's Wii U exclusive Splatoon released a splatfest based on the eponymous series by teaming two characters SpongeBob and Patrick, hosted by the pop band Squid Sisters: Callie and Marie, the event began for 24 hours and Team Patrick won.