As Seen In: Caligula (1979)
Anyone who's ever been all hot and bothered by a mainstream Hollywood sex scene has director Tinto Brass and Penthouse founder Bob Guccione to thank. Working together on Caligula, a racy biopic about the slain Roman emperor, Brass and Guccione ushered big-time cinema into a new age of large-scale exploitation. Caligula is regarded as the first movie to ever feature graphic sex scenes acted out by famous actors. Everything has a starting point.
The filmmakers looked beyond basic humping when making Caligula as hardcore as they possibly could. The dramatization of Caligula's (Malcolm McDowell) assassination is pretty damn explicit, holding little back as the emperor's family is slaughtered and the man himself is repeatedly pierced by spears. The sequence is so gruesome that you'll wish the sex scenes were still in effect. It doesn't take much, though.