Bret Easton Ellis, 1991. Patrick Bateman and the moral void of 80s Wall Street. The decade's most-debated novel.
From Wikipedia
American Psycho is a horror novel by American writer Bret Easton Ellis, published in 1991. The story is told in the first-person by Patrick Bateman, a wealthy, narcissistic, and vain Manhattan investment banker who lives a double life as a serial killer. Alison Kelly of The Observer notes that while "some countries [deem it] so potentially disturbing that it can only be sold shrink-wrapped", "critics rave about it" and "academics revel in its transgressive and postmodern qualities".