The best horror movies work because you feel, in the moment, that what you’re looking at is real. Or even if it isn’t real, you feel like it could happen to you, that it’s not so far-fetched as to be impossible. Plenty of horror movies carve very real feeling scares out of the most outrageous material, from evil Boogeymen to demonically possessed nuns, ghosts and gremlins and Scandinavian cults with weird summertime rituals. Some even pretend, Blair Witch-style, that the events you see onscreen really did happen exactly as you’re seeing them.

But there are also plenty of horror movies whose plots are actually taken from real life. Whenever possible, the posters and trailers and promotional material make sure to spell out in big letters that whatever you’re about to see was BASED ON A TRUE STORY, that it really happened to someone, and so could happen again. Sometimes it’s a little bit of a stretch, and these movies are only very loosely based on their inspiring events, but it always feels a little scarier knowing something like this really did happen.

For this list, we’re celebrating those horror movies that were inspired by real life, whether they’re retellings of famous hauntings or just slasher movies whose villains were inspired by a local serial killer. There’s a little bit of everything in here, from ghost hauntings to witch hauntings to guys running around with chainsaws and sharks and/or crocodiles circling from just beneath the surface. Not everything in these movies is the absolute truth … but some of it is.

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