Mark of the Vampire (1935)

This movie has without a doubt the strangest ending I have ever seen. The movie starts out in a town where vampires are believed to run rampant. Sir Borotyn appears to have been murdered by the head vampire, Count Mora (played by Bela Lugosi), and his daughter, Luna. Professor Zelin (Lionel Barrymore), an expert in vampires, is brought in to help save Sir Borotyn's daughter, Irena, from her father's fate.

I will not ruin the ending for you but I will say I never would have guessed what happened. I also feel that it ruined what could have been a wonderful movie. This movie has the dark and creepy mood that all vampire movies of that era had. This was actually a remake of the 1927 silent film London After Midnight starring Lon Chaney. I'm not sure if that movie had the same stupid ending but this one was ruined for me by that.