14. CaligulaThe heavily edited British version of Caligula contained sex scenes, but they were simulated. This was the version most people could see until the ban on it was wavered in 2008, when the BBFC allowed the uncut version to be released. Said uncut version contains the secret scenes that Bob Guccione, founder of Penthouse magazine and Caligula's financier and producer, filmed, featuring actual sex performed by porn stars. Guccione, fearful that there was not enough sex in the film and wanting to create what was essentially a high-end porn picture, disavowed director, Tinto Brass, and screenwriter, Gore Vidal, and inserted these scenes into the final edit, creating a final film that both Brass and Vidal felt compelled to distance themselves from (Vidal even asked his name to be stricken from the credits). Caligula has one of the most checkered histories of any film on this list, such were the repercussions of its depictions of unsimulated sex, most of which are evident in its notorious, sprawling orgy sequence. Despite this - and despite the abysmal reviews it garnered upon its release - the film has since become a cult classic, the uncut version an undoubted touchstone in cinema's sexual history.