Universal's Dracula, one of the most famous horror films of all time, was originally released in 1931 with an epilogue. It featured Edward Van Sloan, who played Van Helsing, talking to the audience. It ended with him saying "There really are such things as Vampires!".
By the time Dracula was reissued in 1936, The Motion Picture Code (which worked to censor films in order to keep certain morals) was being taken seriously. As such, the epilogue was removed to avoid the wrath of certain religious groups. To this day, no copies of said epilogue have ever surfaced.