I'd like to nominate Apocalypse Now. Very particularly, Marlon Brando's performance. The whole movie is built up to this mythic man, a god among mortals, a figure that human psyche cannot understand, the end to an Odyssey. And Brando and Coppola have managed to surpass all the expectations.
One of the two times I’ve been in a theater where the audience was laughing at what was supposed to be a dramatic performance was Brando’s turn in this film. The other was in Wrath of Kaaaaan.