Every horror movie ends with a credits crawl, and somewhere in that crawl, usually in small type, is the phrase "based on true events" or some lawyer-approved cousin of it. Most of the time that's marketing. Sometimes it isn't. Yahoo just pulled together a roundup of the real stories behind famous horror films, and I went through it the way I go through everything, which is slowly, at an hour I won't admit to.

My read, for whatever it's worth: the real version is almost never supernatural. The culprit is almost always a guy, or a family, or a house with something wrong with it that nobody wanted to spend the money fixing. The demons are set dressing.

Take The Amityville Horror. The 1974 DeFeo murders were real. Six people shot dead in a Long Island house while they slept, and Ronald DeFeo Jr. convicted of all of it. What came after, the Lutz family moving in thirteen months later and fleeing after 28 days claiming demonic voices and oozing walls, has been picked apart so many times that even the people involved have contradicted each other on camera. The house is the only witness that never changed its story and it can't talk. Still gets visitors, though. People park outside and take photos like it might do something.

The Conjuring universe hangs off Ed and Lorraine Warren's case files, and the Perron family haunting in Rhode Island is the load-bearing one. The Perrons maintained for decades that something was in that farmhouse. Skeptics maintained otherwise. Both sides are still arguing and the franchise has been mining that ambiguity for well over a decade now, which is its own kind of eerie.

Then there's Psycho. Norman Bates traces back to Ed Gein, the Plainfield, Wisconsin man whose 1957 arrest shocked the country and whose crimes fed directly into The Texas Chain Saw Massacre's Leatherface and, at a distance, into Buffalo Bill in The Silence of the Lambs. One man in one small town anchored half a century of American horror. You don't need me to list what they found on that farm. You already know, and if you don't, it's one search away and you should think hard about whether today's the day.

The Exorcist goes back to a 1949 case involving a boy from Maryland, codenamed Roland Doe in the Jesuit accounts, who reportedly went through exorcism rituals the priests involved documented in their notes. The boy grew up, lived an ordinary life, and almost never spoke about any of it. I think about that silence more than the head-spinning. The kid got out and chose to say nothing. That's the part nobody makes a movie about.

The roundup keeps going from there, film after film with a real wound somewhere underneath it, and I'd rather you fall down that hole yourself than have me spoil every turn.

What gets me is the pipeline, not the movies. A real family has a real terrible night. The story leaks, decades pass, and eventually a studio options it and adds a ghost. The truth gets sanded down into something more watchable and the original event gets harder to find under the layers. Every one of these cases has a version with the supernatural stripped out and it's just as bad. Sometimes worse.

The movies end. The houses are still standing, and people still drive past them slowly with their lights on.