Mark Of The Vampire (1935)
Plot: When a nobleman is murdered, a professor of the occult blames vampires; but not all is what it seems.
This is a weird little movie. It's also very short. About an hour. It's actually a remake of London After Midnight , a silent movie from 1927 starring Lon Chaney. On the surface, it's a generic vampire movie with Bela Lugosi reprising his role as Drac....Count Mora. Then the end of the movie reveals that Bela is actually an actor who was pretending to be a vampire for the movie. SWERVE. Also, spoilers. Oops.
For some reason, this uploaded with the commentary track, so you can listen to that if you'd like. It's not bad. Just a generic 1930s knock off of Universal horror movies, which kind of becomes a parody once the reveal happens at the end.