Rosemary's Baby (1968)
We don't see much of Rosemary's infernal Don Juan in this horror classic's infamous rape scene, but it's enough to make us fear Ruth Gordon forever. Legend had it that Anton LaVey, founder of Satanism in America, played the Devil in the film. No such luck: The part went to a guy named Clay Tanner, according to IMDB.com--a fellow whose previous credits included "KAOS Agent No. 3" in "Get Smart." He must have done a hell of a job, though (or maybe actors just covet that cool apartment in the Dakota), because A-list talent's been lining up to play the Infernal One ever since.