Fight Club: Brad Pitt and Edward Norton
From a vengeful D.A. to the coolest alter-ego you could ever imagine, Brad Pitt famously played Tyler Durden in David Fincher's 1999 cult classic Fight Club, based on the book by Chuck Palahniuk. Edward Norton plays the film's other lead, referred to only as "Narrator" in the credits, who, together with Pitt's Tyler, founds an underground fight club with only two rules: you do not talk about it and you do not talk about it. The twist to the film is that Tyler and the Narrator are the same person, with Pitt's character merely being a personality created by Norton's because of his own insecurities (we hope we're not spoiling this, it's been a 13 years).