So much of Scream's success with fans hinged on the film's big secrets. It started with the shocking death of Drew Barrymore's character in the opening scene, proving that no one was safe, and ended with the reveal that both Skeet Ulrich's Billy and Matthew Lillard's Stu were the killers. That ending was a massive twist that no one saw coming back in 1996, but Ulrich actually almost spoiled it before his work on Scream actually began.