Clowns were once associated with the circus, then with children's parties, but now they exist in horror movies more than in real life. You might blame John Wayne Gacy, or the Joker, but clowns are just plain scary, and always have been. And now we have another scary clown to look forward to in the new season of American Horror Story and in the a feature film of Stephen King's It coming up. Those clowns are in competition with quite a few past movies that scared the bejesus out of us. Which is your favorite scary clown movie? See the the list of 13 at Gizmodo.