Stephen King knows horror. The bestselling author has been scaring people for more than 50 years now, with the vast majority of his books being turned into memorable horror movies. Because of this, King's thoughts on the genre often get lots of attention. He has an entire non-fiction book about the art of horror, and he often offers up his opinion on horror movies. In a new essay over at Variety, King tackles a loaded subject: the scariest movie ever made. King is smart enough to acknowledge that the concept of something being thought of as the "scariest" is relative. "My conclusion is that the 'scariest' varies according to the viewer's age," King writes. "As a kid of 16, the scariest movie was 'The Haunting' (directed by Robert Wise). As an adult, it was 'The Blair Witch Project,' with that building sense of doom and those truly horrible last 35 seconds.