11. Angela Is The Killer (And A Dude) - Sleepaway Camp
The Ending: The killer is revealed to be introverted Angela (Felissa Rose), and if the sight of her dropping a severed head to the floor wasn't enough, the camera pans out to reveal that she has a penis. That's right, Angela is actually Peter, Angela's brother who was believed to have been killed in an accident with their father, when it was in fact Angela who did, and her mother forced Peter to dress up as a girl and assume her identity. With her mouth hanging open and letting out a creepy gurning noise, the image freezes on her face, before it turns green and the film finally ends.
How It Trolled Audiences: Over 30 years later, the ending to Sleepaway Camp is still regarded as one of the most shocking and creative in horror film history. Had Angela merely been revealed as the killer, nobody would have been massively shocked, and in honesty, the film probably wouldn't be that well-remembered. In serving up this demented, gender-bending twist, audience jaws dropped the world over, and we weren't sure whether to laugh or cry (or both).