Sometimes you'll see a horror film with opening credits that say "Based on a true story." By the time the film is over, you're horrified and wonder what kind of true story it was. Then there are films that say "Inspired by a true story," which could mean anything, since it implies that a story has been greatly altered. Or it could say "Based on a real account" which means little to nothing, because it could be inspired by a hoax, or a story someone else came up with.
That being said, there are a lot of terrifying horror films that were inspired by stories that made the news somewhere at some time. A lot of slasher films drew inspiration from real murders, some you've heard of. Purely supernatural stories about haunted houses are less credible, but movies can be based on what people said happened. And wherever the story came from, they are usually changed enough to make the movie pure fiction. Read about the news stories that led to twenty of our most horrifying movies ever at Bored Panda.
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