2. ‘Bubba Ho-Tep’ — Sequels That Never Happened

'Bubba Ho-Tep' is a horror-comedy that pits an elderly Elvis Presley against a soul-sucking Mummy in a West Texas nursing home. Director Don Coscarelli added a gag at the end of the film, claiming that there’d be a prequel: “Elvis returns in 'Bubba Nosferatu: Curse of the She-Vampires.'” Fans took it seriously, including actor Paul Giamatti who volunteered to play Elvis’ manager, Colonel Tom Parker. Giamatti continues to champion the film, and has since teamed-up with director Coscarelli in the upcoming 'John Dies in the End.' (Watch Giamatti discuss the potential sequel in the video above.)