Patrick Bateman, or "Nasty" as he is often referred to, is the main protagonist and narrator of the 1991 novel American Psycho by Bret Easton Ellis and its 2000 film adaptation. As a serial killer, he kills mostly for sadistic sexual pleasure. He is also a prolific rapist, and has killed many animals.
In the novel, Patrick is a young, handsome, and intelligent man who lives a double life: one as a wealthy Wall Street professional and the other as a remorseless serial killer. He is rich, shallow and addicted to sex, drugs, and conspicuous consumption.
He has a girlfriend, Evelyn Williams, who is also rich and shallow and can't stand him. But they keep dating because of their social lives. He is a handsome and intelligent man who lives a double life: as a wealthy Wall Street professional and the world's most remorseless serial killer. At night, he goes into a state of trance and commits murder.
He is wealthy and well educated, but he doesn't know how to control his impulses. He is obsessed with detail and obsessively records everything he owns, including his designer clothes, expensive stereo equipment, a great Business card, and alcoholic drinks. His character was originally intended to be played by Christian Bale, but the director Roger Avary asked him not to. It was then that Ellis himself was approached to play the part, but he turned down it.