10 Times The Movie Killer Was Hiding In Plain Sight
3. Azazel - Fallen

This 1998 Denzel Washington-starring cult classic thriller may be a little rough around the edges, but it benefits enormously from a deliciously clever final twist, which totally re-jigs everything we thought we knew.
The supernatural detective film opens with a quote from protagonist Detective John Hobbes (Denzel Washington), who says, "I want to tell you about the time I almost died," as a clip of Hobbes on the verge of death, clearly implied to be from the end of the movie, is shown.
And while the sequence we see is indeed from the film's final scene, the context of this quote is ultimately totally different.
The film ends with Hobbes discovering that Detective Jonesy (John Goodman) is possessed by the fallen angel Azazel, and in order to ensure that Azazel cannot enter a new host, Hobbes kills Jonesy before smoking a poisoned cigarette, killing himself in the hope of leaving Azazel stranded in the wilderness in a dead body.
Except, the voiceover then picks up once again, and we realise that it wasn't actually Hobbes at all but Azazel, who possesses Hobbes in his final moments as he's on the verge of death - as seen in the opening of the movie.
As such, it was Azazel that almost died, not Hobbes, who actually did die. At that moment, Azazel manages to possess a nearby cat, with the implication that he will return to civilisation to possess another human. Yup, the bad guy actually won.
It's a terrifically clever twist that totally redefines the meaning of that opening sequence, by literally having the villain speak to a blissfully unaware audience under the guise of actually being the hero.