50 Movies Where Evil Won

Plot: Two detectives - burned-out veteran William Somerset (Morgan Freeman) and brash rookie David Mills (Brad Pitt) - hunt for a sadistic serial killer who is modelling his murders on the Seven Deadly Sins.

Towards the end of this serial killer masterpiece, John Doe (Kevin Spacey) - the serial killer responsible for the murders - abruptly hands himself in and says that he can take Somerset and Mills into the desert, where they will find the bodies of his last two victims. They follow his instructions, and are promptly delivered a box containing the severed head of Mills' pregnant wife Tracy (Gwyneth Paltrow). 

Doe explains that he was jealous of Mills' normal family life, and he murdered Tracy to represent the sin of Envy; now, he wants Mills to shoot him dead and become Wrath, thus completing Doe's scheme. Tragically, despite Somerset's pleas, Mills does indeed kill Doe, completing John Doe's horrendous quest and leaving his own life destroyed. 

David Fincher had to fight for this ending. The studio wanted something more upbeat, but Fincher, no doubt extra-cautious after his debut film Alien 3 was nuked by studio interference, held his ground and won out. The result was one of the greatest, most haunting climaxes in movie history, an unforgettable victory for one of cinema's greatest psychopaths.