It is the second season in the Monster anthology series, following Dahmer – Monster: The Jeffrey Dahmer Story. Having initially ordered the program in 2020 as a limited series, Netflix announced in 2022 that it had been renewed as an anthology series, with two further editions based on the lives of "other monstrous figures". The second season, which focuses on the Menendez brothers, was announced to be in development on May 1, 2023.

Upon its premiere on September 19, 2024, the season received mixed reviews from critics, who praised the performances (particularly those of Bardem and Koch) and the fifth episode but criticized its runtime, inconsistent tone, and the incestuous portrayal of the Menendez brothers. Erik Menendez denounced the season for its inaccuracies and Lyle's characterization. It achieved global commercial success, debuting as the number-one series on Netflix worldwide. At the 82nd Golden Globe Awards, it earned three nominations: Best Limited or Anthology Series or Television Film, Best Actor – Miniseries or Television Film for Koch, and Best Supporting Actor – Series, Miniseries or Television Film for Bardem.

A third season, titled The Original Monster, is currently in production, starring Charlie Hunnam as murderer and graverobber Ed Gein.

Monsters: The Lyle and Erik Menendez Story chronicles the case of the real-life brothers convicted in 1996 for the murders of their parents, José and Kitty Menendez. While the prosecution argued they were seeking to inherit their family fortune, the brothers claimed—and remain adamant to this day, as they serve life sentences without the possibility of parole—that their actions stemmed out of fear from a lifetime of physical, emotional, and sexual abuse.

• Javier Bardem as José Menendez:
  Lyle and Erik's father. Born in Cuba, he is a wealthy and powerful businessman in the entertainment industry, serving as an executive at RCA Records and the CEO of Live Entertainment. He is described as an ambitious and controlling father who imposes high expectations on his sons. Lyle and Erik allege that they killed José in self-defense after years of sexual, physical, and emotional abuse. This marks the first series regular role for Bardem, who has primarily worked in major films. He described José as "this commanding man [who] really thinks and feels that he's absolutely right all the time, and that has to be obeyed by others." Speaking to TheWrap, he admitted that he was initially unfamiliar with the case, but after "digging in and informing [himself]", he was alarmed by the extent of the alleged sexual abuse.
• Chloë Sevigny as Mary Louise "Kitty" Menendez:
  Lyle and Erik's mother who struggles with mental health issues, including depression, alcoholism, and substance abuse. After the murders, Lyle and Erik claim that Kitty had been complicit in the alleged abuse they suffered from their father. In describing Kitty, Sevigny expressed doubt about whether Kitty intentionally ignored the sexual abuse the brothers claim they endured from their father. She connected with a director whose wife was friends with Kitty, stating, "I'm trying to get in touch with her to hear her personal accounts, which I generally don't like to do, but there's so much negative stuff about Kitty that I feel like it could be really beneficial to hear from someone that did know her."
• Cooper Koch as Erik Menendez:
  The younger Menendez brother, who, along with his older brother Lyle, killed their parents in 1989. An 18-year-old tennis player, he is depicted as the more sensitive brother grappling with guilt, depression, and emotional trauma. Koch previously auditioned for the role of Erik Menendez in the 2017 NBC limited series Law & Order True Crime: The Menendez Murders and the Lifetime television film Menendez: Blood Brothers. Prior to the season premiere, Koch had a phone call with Lyle and Erik, and they later met at Richard J. Donovan Correctional Facility for Kim Kardashian's project on prison reform. On his dedication to the role, Koch explained, "I just really wanted to do as much research and dig really deep into myself to really portray [Erik] with integrity and just be as authentic as possible to support him, and also to support his family and all the people who stand with him." Erik praised Koch's performance, stating, "I've heard nothing but great things about [Koch] and about episode five, and that [he's] going to win an Emmy. And I hope that [he does]."
• Nicholas Alexander Chavez as Lyle Menendez:
  The older Menendez brother, who, along with his younger brother Erik, killed their parents in 1989. A 21-year-old aspiring businessman and Princeton University student, he is depicted as the more confident, intense, and aggressive brother who is protective of Erik. Chavez revealed that he had no prior knowledge about the case before auditioning for the role. In preparation, he said he "had to do an extensive amount of research" and described Lyle as a "compelling and complicated character".
• Ari Graynor as Leslie Abramson:
  Erik's lead defense attorney. A notable criminal defense lawyer in Los Angeles, she is known for her tenacious and aggressive courtroom style. Graynor stated, "[Leslie] is an extraordinary lawyer, but she was an extraordinary person, and such a spirit, and fierce and loving." She revealed that she didn't reach out to Abramson while preparing for her role, as she knew the attorney "had made it pretty clear that she never wanted to speak about any of her cases".
• Nathan Lane as Dominick Dunne:
  A prominent journalist known for his keen interest in high-profile criminal cases. Dunne becomes a key voice in shaping public perception of the brothers' story through his article The Nightmare on Elm Drive for Vanity Fair. He holds resentment against defense attorneys and murderers after the death of his daughter, Dominique Dunne, and the subsequent acquittal of her ex-boyfriend and killer. Lane described Dunne as "a passionate advocate for victims and [that's] why he's looking out for José and Kitty". He also approached Dunne's son, actor and director Griffin Dunne, who offered his perspective on the trial of John Sweeney for the murder of his sister.

• Dallas Roberts as Dr. Jerome Oziel, Erik's therapist to whom Erik confesses the murders.
• Jason Butler Harner as Det. Les Zoeller, a Beverly Hills Police detective assigned to investigate the deaths of José and Kitty.
• Leslie Grossman as Judalon Smyth, Dr. Oziel's mistress who becomes entangled in Lyle and Erik's case.
• Marlene Forte as Marta Cano, José's sister.
• Larry Clarke as Brian Andersen, Kitty's brother.
• Charlie Hall as Craig Cignarelli, Erik's best friend who, along with Erik, co-wrote a screenplay about a kid who kills his wealthy parents for the inheritance.

• Jeff Perry as Peter Hoffman, an executive at Live Entertainment and José's business acquaintance.
• Jade Pettyjohn as Jamie Pisarcik, Lyle's girlfriend at the time of the murders.
• Tanner Stine as Perry Berman, Lyle and Erik's friend.
• Enrique Murciano as Carlos Baralt, José's brother-in-law and the executor of the Menendez family's estate.
• Anthony Turpel as Donovan Goodreau, Lyle's friend whose driver's license was used to purchase the shotguns.
• Drew Powell as Det. Tom Linehan, a Beverly Hills Police detective and Det. Zoeller's partner.
• Michael Gladis as Tim Rutten, Leslie's husband who is a journalist for the Los Angeles Times.
• Gil Ozeri as Dr. William Vicary, a therapist who examines Erik for the trials.
• Salvator Xuereb as Robert Shapiro, Erik and Lyle's first criminal defense attorney.
• Brandon Santana as Tony, an inmate at LA County Jail who becomes sexually involved with Erik.
• Tessa Auberjonois as Dr. Laurel Oziel, Dr. Oziel's wife.
• Jess Weixler as Jill Lansing, Lyle's lead defense attorney in the first trial.
• Milana Vayntrub as Pam Bozanich, a prosecutor in the first trial.
• Paul Adelstein as David Conn, a prosecutor in the second trial.
• Patrick Breen as a jury alternate who replaces Leigh in the second trial.
• Vicki Lawrence as Leigh, a juror in the second trial.

Monster was initially ordered as a limited series based on the serial killer Jeffrey Dahmer. On November 7, 2022, Netflix announced that it had been renewed as an anthology series based on famous convicted killers. On May 1, 2023, it was confirmed the second season, titled Monsters, would focus on Lyle and Erik Menendez, brothers convicted of the 1989 murders of their parents in Beverly Hills, California. Showrunners Ryan Murphy and Ian Brennan revealed that the project was inspired by the popularity of the case on TikTok and Instagram, where creators have sparked a movement to free the brothers.

In June 2023, Cooper Koch and Nicholas Alexander Chavez were cast as Erik and Lyle Menendez, respectively. In January 2024, Javier Bardem and Chloë Sevigny joined the cast as José and Kitty, respectively, with Nathan Lane being cast as journalist Dominick Dunne. In February, Ari Graynor joined as Erik's defense attorney, Leslie Abramson. Leslie Grossman was added that same month as Judalon Smyth.

Production for the season was initially set for September 2023, but was postponed due to the 2023 Hollywood labor disputes. Principal photography took place from March to July 2024 in Los Angeles. Julia and Thomas Newman composed the original score. The official soundtrack album was released on various streaming platforms on September 13, 2024, prior to the release of the season.

The red carpet premiere was held at Grauman's Egyptian Theatre in Los Angeles on September 17, 2024. Monsters: The Lyle and Erik Menendez Story was released on Netflix on September 19, 2024.

The season debuted at the number-one spot on Netflix worldwide, garnering 12.3 million views (or 97.5 million hours viewed) within just four days of its release. On its second week, it remained the most-watched series on the platform after earning 19.5 million views (or 153.8 million hours viewed). It received 13.1 million views (or 103.6 million hours viewed) on its third week and 8.7 million views (or 68.6 million hours viewed) on its fourth week. On the Nielsen Streaming Chart, it debuted with 1.72 billion minutes watched, and had a 40% rise on its second week with 2.4 billion minutes watched, the highest since Bridgerton in June 2024.

On the review aggregator website Rotten Tomatoes, 47% of 30 critics' reviews are positive, with an average rating of 5.0/10. The website's consensus reads: "Well-acted but off-puttingly sordid, Monsters leaves viewers feeling guilty without enough pleasure to compensate." Metacritic, which uses a weighted average, assigned a score of 47 out of 100 based on 12 critics, indicating "mixed or average" reviews.

Aramide Tinubu of Variety described Monsters as "overlong and exhausting". While she praised the first half and cited the fifth episode ("The Hurt Man") as a "standout", she noted that the season "falls into the deep end" afterward. Tinubu also praised the "outstanding performances", but overall found the season's narrative to be "futile and bizarre". Inkoo Kang of The New Yorker similarly commended the fifth episode as "some of Murphy's most moving and startling work in ages", but the remaining episodes "attempt to reconcile the horror of abuse with the horror of the brothers' retributive violence". In a review for The Hollywood Reporter, Daniel Feinberg described the season as "unjustifiably long", but praised the fifth episode for its "precise" writing and Cooper Koch's performance. Moreover, Feinberg commended Javier Bardem's performance, calling him "terrifying in a performance that's wildly outsized but offers enough subtlety to position his howling patriarch as both a chilling villain and as a victim himself".

Writing for The Hindu, Pallavi Keswani criticized the season as "a sensational mess, so occupied with the ornamentation of facts that it loses the plot halfway through". Similarly, Kayleigh Donaldson of TheWrap described it as "an overlong slog that never commits to the ideas it sets up" and feels "something giddily salacious rather than a portrait of familial trauma". Donaldson further noted that, despite dealing with sensitive topics such as sexual assault and child abuse, it becomes "hugely misguided" for focusing on "sensuality, with the brothers both forever in Speedos and shot as though the series was a perfume ad".

The season received backlash for implying an incestuous relationship between the Menendez brothers. Writing for The Hollywood Reporter, Kevin Dolak specified some of the scenes with incest innuendos: "In the second episode, this includes the brothers briefly kissing after Lyle has placed his hands on Erik's neck; later in the same sequence, Lyle is seen cutting in on Erik while he's dancing with a woman at a party in their room at the Hotel Bel-Air, then wiping cocaine from his nose and sticking his thumb in his brother's mouth. Later, in an episode seven sequence that is pretty clearly telegraphed as a moment of fantasy, mother Kitty Menendez ascends a staircase to find her sons showering together." Nicole Vassell from Glamour described the incestuous portrayal as "a jarring addition to a story that is already tough to stomach". In an article for TheWrap, Kayleigh Donaldson stated that the brothers' "co-dependency stemming from their father's molestations [...] are spun into a forbidden romance of sorts". Viewers have also accused it of sensationalizing the brothers' abuse and turning it into a "fictitious relationship".

Trial expert and journalist Robert Rand, author of the 2018 book The Menendez Murders, labeled the incest allegations as "fantasy" and pointed out that there was no credible evidence to support such claims. He explained that while some rumors circulated during the trial, they were baseless, and the series distorted the brothers' relationship for dramatic effect. Lyle Menendez also testified at his trial that he never had a sexual relationship with his brother. In response, Murphy defended the incestuous depiction as an "obligation for storytellers", stating, "What the show is doing is presenting the points of view and theories from so many people who were involved in the case. Dominick Dunne wrote several articles talking about that theory." Vanity Fair clarified that Dunne never suggested such a theory in his reporting for the publication.

On September 20, 2024, Erik Menendez released a statement through his wife's X account, stating:

I believed we had moved beyond the lies and ruinous character portrayals of Lyle, creating a caricature of Lyle rooted in horrible and blatant lies rampant in the show. I can only believe they were done so on purpose. It is with a heavy heart that I say, I believe Ryan Murphy cannot be this naive and inaccurate about the facts of our lives so as to do this without bad intent.

It is sad for me to know that Netflix's dishonest portrayal of the tragedies surrounding our crime have taken the painful truths several steps backward – back through time to an era when the prosecution built a narrative on a belief system that males were not sexually abused, and that males experienced rape trauma differently than women. Those awful lies have been disputed and exposed by countless brave victims over the last two decades who have broken through their personal shame and bravely spoken out. So now Murphy shapes his horrible narrative through vile and appalling character portrayals of Lyle and of me and disheartening slander.

Is the truth not enough? Let the truth stand as the truth. How demoralizing to know that one man with power can undermine decades of progress in shedding light on childhood trauma. Violence is never an answer, never a solution, and is always tragic. As such, I hope it is never forgotten that violence against a child creates a hundred horrendous and silent crime scenes darkly shadowed behind glitter and glamor and rarely exposed until tragedy penetrates everyone involved. To all those who have reached out and supported me, thank you from the bottom of my heart.

Addressing Erik's response, showrunner Ryan Murphy explained, "There were four people involved in that— two of them are dead, and two of them are alive with their point of view. But what about the parents? We had an obligation as storytellers to also try and put in their perspective based on our research, which we did." In a different interview, he mentioned that he has no interest in meeting the Menendez brothers, but expressed his belief that a new trial could be possible. Nathan Lane, who portrayed Dominick Dunne, added, "[Erik] hasn't seen the show. He's just criticizing it and condemning it without ever having seen it, so one has to take that with a grain of salt." Meanwhile, Nicholas Alexander Chavez, who played Lyle Menendez, responded to Erik with "sympathy and empathy", but clarified that "the show aims to fill out a lot more details than just the courtroom scenes".

Reflecting on Erik's criticism, Cooper Koch, who portrayed him, said, "It definitely affected me and it made me feel things [...] I understand how difficult it would be to have the worst part of your life be televised for millions of people to see. It's so exposing. I understand how he feels and I stand by him." Koch voiced his support for the brothers and their claims of sexual abuse, revealing that he discussed Erik's criticisms with him during their meeting at Richard J. Donovan Correctional Facility. During this visit, Koch also met Lyle and over 30 other inmates as part of a prison reform meeting led by Kim Kardashian.

On September 25, 2024, Lyle and Erik Menendez's family and relatives issued a statement regarding the season, describing it as "a phobic, gross, anachronistic, serial episodic nightmare". They added, "Our family has been victimized by this grotesque shockadrama. [...] Perhaps, after all, Monsters is all about Ryan Murphy." In defense, Murphy claimed that Monsters is "the best thing that's happened to [the Menendez brothers] in 30 years", referring to the renewed public interest in their case following the season's commercial success.

At Monsters' red carpet premiere in Los Angeles, Murphy announced that the third season of the anthology series will center on Ed Gein, with Charlie Hunnam starring as the serial killer. On October 4, it was confirmed that the season would be titled The Original Monster, exploring Ed Gein's life as the first "celebrity serial killer" and examining how true crime evolved into a pop culture phenomenon.

Murphy expressed his interest in extending the season with "one or two episodes". He stated, "It's been discussed. [...] Everyone has been interested in that. I think everyone wants to see how this story ends because this story is not over." However, he noted that this would depend on whether Koch and Chavez, who play Erik and Lyle, respectively, agree to reprise their roles. When asked whether he would return, Koch replied, "I don't know, I don't think so. I think we told the story and [...] I think it's good where it is now."

• Monsters: The Lyle and Erik Menendez Story on Netflix
• Monsters: The Lyle and Erik Menendez Story at IMDb