Universal's Dracula, one of the most famous horror films of all time, was originally released in 1931 with an epilogue taken from the play of Dracula that was the basis of the movie. 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!". The scene was a curtain call speech, which Van Sloan would respire for the opening of Frankenstein which he also played the role of Dr. Waldman, the difference was that he was warning the audience about the film.
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.
Update: In the 1999 Documentary The Road to Dracula, the Epilogue is shown in stills and even a film clip was shown, it was never explained why the whole clip wasn't used but due to the clearly decayed look the final sentence might of been just usable. It is unknown if the reel can be restored or not.