Based on the 1991 novel by Bret Easton Ellis, it stars Christian Bale as Patrick Bateman, a New York City investment banker who leads a double life as a serial killer alongside an ensemble cast of Willem Dafoe, Jared Leto, Josh Lucas, Chloë Sevigny, Samantha Mathis, Cara Seymour, Justin Theroux, and Reese Witherspoon.

[7] In 1987, New York City investment banker Patrick Bateman spends most of his time dining at popular restaurants while keeping up appearances for his fiancée, Evelyn Williams, as well as his circle of wealthy associates, most of whom he hates.

Enraged by the superiority of his colleague Paul Allen's card, Bateman finds a homeless man in an alley to whom he initially offers help, before denigrating him, stabbing him, and stomping his dog to death.

Bateman calls his lawyer, Harold Carnes, and leaves a frantic voicemail in which he confesses to about 40 murders - including Christie, Elizabeth, the model, several homeless people, a former girlfriend, and Paul Allen - over a period of six months, and admits to having eaten some of their brains.

Disturbed by Bateman's agitated state, Jean explores his office and in a desk drawer finds a journal full of detailed, graphic drawings of murder and mutilation.

The film is an adaptation of the satirical novel American Psycho by Bret Easton Ellis, which was published in 1991 amid significant controversy over its graphic depiction of violence against women.

[11] It ended with an elaborate musical sequence to Barry Manilow's "Daybreak" atop the World Trade Center, a change which Ellis felt exemplified how bored he was with the material.

[8][16] Harron was ambivalent towards the other "very mainstream and boring" offers she was receiving following I Shot Andy Warhol and decided to make American Psycho due to its "risky" nature.

[21] Harron spoke with Ben Affleck, Matt Damon, Edward Norton, and Vince Vaughn, but after they all declined, Lionsgate begrudgingly agreed to hire Bale with a small $50,000 salary.

[9] By that point, Dafoe, Leto, Reese Witherspoon, and Chloë Sevigny were already committed; Harron and Bale unsuccessfully tried to convince Winona Ryder to play Evelyn Williams.

The blood covered only half of Bale's face by accident but Harron found this "a perfect metaphor for the Jekyll-and-Hyde aspect of Bateman: pristine on the outside, bloody and psychotic on the inside".

[29] American Psycho's soundtrack features licensed 1980s pop music from a variety of artists, including David Bowie, Phil Collins, the Cure, the Mediæval Bæbes, New Order, Robert Palmer and Eric B.

The Huey Lewis and the News song "Hip to Be Square" appears in the film and was intended to be on the soundtrack album, but was removed, forcing Koch Records to recall approximately 100,000 copies.

[33] Cale was uninvolved with the selection of licensed music and sound mixing, though, for one scene that Harron wanted to be unsettling, he suggested using animal noises, like the tapes of rabbits screaming that the Federal Bureau of Investigation used against the Branch Davidians during the Waco siege.

The e-mails also describe or mention interactions with other characters from the novel, including Timothy Price (Bryce in the film version), Evelyn, Luis, Courtney, David, Detective Kimball, and Marcus.

[36] Lionsgate spent $51,000 on an online stock market game, Make a Killing with American Psycho, which invited players to invest in films, actors, or musicians using fake Hollywood money.

[44] Sony Pictures Home Entertainment also released the film on Blu-ray around Australia, Spain, Poland, Russia, South Africa, Bulgaria, China, the Czech Republic, Hungary, Portugal, Thailand, and Taiwan in December 2008.

[23] Upon its theatrical release, the film received positive reviews in crucial publications, including The New York Times which called it a "mean and lean horror comedy classic".

The website's critical consensus reads: "If it falls short of the deadly satire of Bret Easton Ellis's novel, American Psycho still finds its own blend of horror and humor, thanks in part to a fittingly creepy performance by Christian Bale".

[48] Roger Ebert gave the film three out of four stars, praising the female perspective brought by Harron and Turner because they depict Bateman not as a psychologically disturbed aberration, but as a certain type of selfish, ego-driven male behavior taken to an extreme.

[49] In his review for the Los Angeles Times, Kenneth Turan wrote: "The difficult truth is that the more viewers can model themselves after protagonist Bateman, the more they can distance themselves from the human reality of the slick violence that fills the screen and take it all as some kind of a cool joke, the more they are likely to enjoy this stillborn, pointless piece of work".

[52] Rolling Stone's Peter Travers wrote: "Whenever Harron digs beneath the glitzy surface in search of feelings that haven't been desensitized, the horrific and hilarious American Psycho can still strike a raw nerve".

[53] In a somewhat positive review for Slate magazine, David Edelstein noted the toned-down brutality and sexual content in comparison to the novel and wrote that the moment where Bateman spares his secretary is when "this one-dimensional film blossoms like a flower".

[54] Owen Gleiberman gave the film an "A−" rating, writing for Entertainment Weekly: "By treating the book as raw material for an exuberantly perverse exercise in '80s Nostalgia, Harron recasts the go-go years as a template for the casually brainwashing-consumer/fashion/image culture that emerged from them.

[55] Time magazine's Richard Corliss wrote that "Harron and co-screenwriter Guinevere Turner do understand the book, and they want their film to be understood as a period comedy of manners".

19 in its list of the "Top 20 Horror Films of the Decade", with the article praising "Christian Bale's disturbing/darkly hilarious turn as serial killer/Manhattan businessman Patrick Bateman, a role that in hindsight couldn't have been played by any other actor.

[59] He also said that while the book attempted to add ambiguity to the events and to Bateman's reliability as a narrator, the film appeared to make them completely literal before confusing the issue at the very end.

Ellis appreciated that the film clarified the humor for audiences who mistook the novel's violence for blatant misogyny as opposed to the deliberately exaggerated satire he had intended, and liked that it gave his novel "a second life" in introducing it to new readers.

[69] Finnish melodic death metal band Children of Bodom used the film's ending monologue "My pain is constant and sharp and I do not hope for a better world for anyone" as a segue between two songs on their 2003 album Hate Crew Deathroll.

[76] American metalcore band Ice Nine Kills wrote a song based on the film for their 2021 album The Silver Scream 2: Welcome to Horrorwood called "Hip to Be Scared" and features Papa Roach vocalist Jacoby Shaddix.