Ambiguous Disorder: Seems to have Borderline Personality Disorder (in addition to his narcissism, sadism, and sociopathy), as this would explain his hallucinations as well as some other things he reports, such as identity disturbance, his mood swings, and his tendency to not feel much of anything.
Asshole Victim: He finally receives his comeuppance in the novel Lunar Park when he gets trapped in a pier fire. He really had it coming to say the least.
Attention Whore: Confesses his crimes near the end because he wants people to know him and because he wants to matter! It doesn't work as no one believes him and his crimes may have been all just a fantasy. In the end, no one will give a shit about him, no matter how hard he tries.
Bad People Abuse Animals: In both the movie and the book, he stomps a dog to death that belonged to a homeless man he previously stabbed. In a chapter in the book, he disembowels another dog, then shoots its owner; in a chapter set at a zoo, he throws nickel coins to the seals, just because he saw a table asking people not to do so (because they can choke on them).
Beneath the Mask: Publicly, he's charming, mild-mannered, and likable to those in his circle of friends. Privately, he's a violent sadist incapable of empathy, remorse, or compassion. He explicitly refers to his friendly facade as his "mask of sanity".
Distracted by My Own Sexy: During the porn film he's making with two prostitutes, he spends more time looking at himself in a mirror, flexing his biceps.
Even Evil Has Standards: Of all the horrendous atrocities he's committed, including murder, cannibalism, and so on, Bateman draws the line at anti-Semitic remarks. Or seems to. (In the book he has an argument in a Jewish deli and insults the people running it.)
Evil Is Petty: Almost all of his murders are motivated by people having nicer clothes or better apartments than he does.
Fate Worse Than Death: Trapped in a shallow world of greed and hatred than he despises as much as he detests himself. All while knowing that nothing he does will ever be of any consequence.
Early in the narrative, he publicly puts forth to his peers that it is on themselves to work towards solving social crises, such as providing food and shelter for the homeless, opposing racial discrimination, supporting civil rights and equal rights for women, and return to traditional moral values. However, privately, Bateman is an ardent bigot without ethics who only feels disgust for the poor.
In the book, as Bateman lays this all out, he even tries to openly support both sides of divisive social issues, such as stressing a need to "change abortion laws to protect the life of the unborn while also maintaining a woman's right to choose," which is further contradicted later in the book in separate scenes where Bateman forces women who he sleeps with to get abortions even performing several of them himself against their will.
Patrick shows open disdain for people who smoke cigarettes, while he himself enjoys smoking cigars.
In the film, Patrick disallows one of the prostitutes from smoking in his apartment after she takes out a cigarette, but Patrick lights a cigar in the exact same room after murdering Paul Allen.
In the book, Patrick loudly complains about being seated next to smokers at a restaurant (hoping the "nicotine addicts" hear him and feel guilty about their habit) when meeting with his ex-girlfriend Bethany. Later, when torturing Bethany back at his apartment, Patrick momentarily pauses to show her a cigar and gloat that he still smokes them, in spite of telling her earlier that he had quit.
Patrick chides his colleagues for making anti-semitic comments about another one of their co-workers and confusing words like "menorah" and "dreidel", but in the book, while suffering some kind of mental breakdown, Patrick wanders into a kosher deli and repeatedly tries to order a cheeseburger and milkshake, failing to understand the waitress when she explains that they don't serve anything with dairy products and believing the waitress to be the one who is having a problem. When the manager approaches Patrick, he stands up and shouts anti-semitic slurs and insults before storming out back onto the street.
I'm a Humanitarian: In the book, he eats the brain and part of the insides of one of his victims, and later bursts into tears while cooking another... because he thinks he's doing it wrong and can't cook. In the movie, eating people's brains is one of the things Patrick confesses to his lawyer.
Inferiority Superiority Complex: Despite his insane levels of narcissism, it is shown often that Bateman utterly detests himself as much as he does everyone else and most of his murders are motivated by people unintentionally reminding him of this.
It's All About Me: The only people he refuses to kill are ones who profess some affection for him, all of which he coldly discards.
The Movie Buff: He's a very avid fan of horror films and gory B-movies, which he often rents on VHS. He frequently rents Body Double in the novel, is seen watching The Texas Chainsaw Massacre 1974 in the film, and regularly enjoys A Nightmare on Elm Street (1984) in the musical. In both the novel and musical, Bateman's associates grow tired with him always talking about movie killers like Leatherface from Texas Chainsaw Massacre (which causes Patrick much annoyance when they also mistakenly call the character "Featherhead"). In the musical, Patrick also makes passing references to C.H.U.D., mentions watching Silent Night, Deadly Night prior to attending Evelyn's Christmas party, and considers Freddy Krueger an "American icon".
One-Hour Work Week: His job is very high-paying, with a cushy office, but he doesn't seem to do any actual work there and has a lot of free time on his hands. In the various adaptations of the story, Patrick's time at his office is spent watching TV, listening to music on his walkman, doing crossword puzzles, lifting weights, and any number of other unrelated activities. Famously, when Patrick and all his associates attend a business meeting, the time is spent showing off their business cards, and later, when Patrick attempts to look busy when visited by Detective Kimball, all Patrick can think to do is pick up his phone receiver and ramble on about men's fashion and proper tipping etiquette, rather than pretend to actually be in the middle of business. When his secretary looks through his day planner, it's almost empty save for lunch dates (plus doodles in the film). It's mentioned both in the book and the film that it's his dad's company. In his review of the film, Roger Ebert mused that Patrick's spree might have been averted if he'd been put to work hitting nails with a hammer, which is about the only task he's qualified for.
Overly Nervous Flop Sweat: He does this a lot when under pressure or when coming close to getting caught in a lie. According to Word of God, Christian Bale was so talented an actor that when doing repeated takes of the famous business card scene, he was capable of sweating on cue.
Pop-Cultured Badass: Deconstructed. He tries to define himself through his appreciation for music, art, and pop culture and relates this much to the reader/audience, but his grasp and understanding of his favorite music and artists is reduced to what material they make the most appealing to the widest audiences and Lowest Common Denominator, such as dismissing early Genesis albums with Peter Gabriel (and his "lame solo career") as being "too artsy, too intellectual" and favoring the more commercially-driven direction of the group after Phil Collins became the group's frontman. Other assessments he makes of popular singers and bands are frequently off-the-mark and factually wrong, like being convinced that Whitney Houston is a jazz singer or believing "You Can't Always GetWhat You Want" is a song by The Beatles. Elsewhere, he often speaks of owning what's described as the original version of "Sunrise with Broken Plates"◊ by artist David Onica (while discreetly boasting of the high cost he paid to obtain it), only for his ex-girlfriend to point out to him that he hung it upside down. All of this only serves to further demonstrate Patrick's shallowness and delusions about having "good taste."
Psychopathic Manchild: A very subtle case, but his demeanour behind his Mask of Sanity is rife with this, with things like murdering people over having better stuff than he has and desperately trying to garner attention for himself make him come off as a petulant brat having frequent tantrums because no one's paying attention to him.
Purely Aesthetic Glasses: He seems to just wear them because they are designer and because all his other Yuppie friends wear the same thing.
Pyrrhic Villainy: By the end of the book, it's clear that all of Patrick's evil and depravity have afforded him nothing. He's still as lonely and miserable and empty as he was at the beginning, and no one gives a shit about him.
Raincoat of Horror: He wears a clear plastic raincoat over his suit, to prevent it from being stained with blood.
Sadist: Gets off on causing pain. But Patrick knows even if he's doing something like that, it'll never bring any consequences. EVER.
Some details in the book suggest a possibility that there may be one or more other serial killers on the loose and acting independently of—but very similar to—Bateman. In the first chapter, for instance, Patrick details a story in a day's newspaper about the disappearances of two people aboard a yacht belonging to a New York socialite who are believed to have been attacked with a machete and dumped off the boat; Patrick seems to have nothing to do with this. Later, Detective Kimball makes explicit reference to "a young stockbroker" in New Jersey who had been arrested and charged with murder and using corpses in "performing voodoo rituals".
Patrick is obsessed with real serial killers like Ted Bundy or Ed Gein, to the point that his friends complain that he always brings them up in conversations.
The Sociopath: Informs everything about his life — the film's director describes him as a Martian trying to imitate human behavior (and never quite hitting the mark). He is probably one of the best examples in media.
Straw Hypocrite: He often espouses lofty political ideals in public like taking care of the poor or fighting discrimination and sexism. Bateman himself knows he's just bullshitting to hide his true nature, as privately he not only holds numerous racist, elitist, and sexist views, but he's also a psychotic murderer who frequently kills women, minorities, and homeless people.
Tall, Dark, and Handsome: As we learn during his narration of his morning routine, he is the pinnacle of physical perfection.
They Look Just Like Everyone Else!: While he's superficial and phony, no one notices how facile his persona is. Even his obsessive grooming habits go unnoticed, since he blends right in with the rest of the self-absorbed yuppie crowd. In fact, Patrick is constantly mistaken for other people in his circle.
Through the Eyes of Madness: Patrick has bizarre hallucinations he believes to be true. For instance, he once sees that a Cheerio is the guest on his favorite talk show and an ATM tells him to feed it a cat.
The Unsmile: His used car salesman grin becomes even more comical when he's agitated.
Villain Protagonist: A Serial Killer with a host of disorders making him Ax-Crazy. Our central focus, everyone. And even if he's just imagining the murders, he's still an unlikable, self-centered, elitist, racist, shallow bastard.
Wicked Pretentious: He makes a pretense at being an aficionado of fine food, clothing, and music. Close inspection will reveal that he's only interested in these things because they're popular fads, and actually has little understanding of any of the subjects.
Would Hurt a Child: He stabs a small boy to death just to see if he'd enjoy it. He doesn't... because he doesn't find it evil enough.
You Are What You Hate: He despises his friends because they represent parts of himself that he hates and remind him of what he doesn't have.