Horror Movies Based On Even Scarier True Stories

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"Based on a True Story": it's the oldest trick in Hollywood marketing, and horror fans have read variations on those words countless times. Whether a movie actually delivers scares on its "fact-based" premise is one of the great crapshoots of horror fandom, but the gimmick has been a pretty safe bet at the box office. The blurrier the line between fact and fiction, the bigger the potential scares—but sometimes, the stories behind the scenes are even more terrifying. From the pathological to the paranormal, here are few of the truly terrifying stories that inspired the genre's most memorable scares. 

The Oscar-winning 1973 film The Exorcist was based on the 1949 possession of a Maryland boy named "Roland Doe," a boy who reportedly underwent an exhausting battery of exorcisms performed by Jesuit priests. While skeptics maintain that "Doe" was simply insane, the phenomenon of "demonic possession" has been traced to Biblical times and is taken very seriously by religious experts—and although neither spinning heads nor projectile vomit have been widely reported, levitations, shaking beds, and speaking in tongues have.

Green vomit aside, director William Friedkin claims his sole interest was to immortalize the events and circumstances surrounding Roland's case; in so doing, he created one of the most widely acclaimed horror movies of all time, It's the real-life mysteries that inspired it, however, that make it the most horrifying. Not scared yet? Consider that the demand for exorcisms has rapidly increased in recent years: in 2015, the Catholic Church reported having as many as 100 requests at any given time.

Some of the scariest and best-known characters in horror have been drawn from the pages of serial killer Ed Gein. Gein's grisly murder spree inspired Leatherface of The Texas Chainsaw Massacre, Norman Bates of Psycho, and Buffalo Bill of The Silence of the Lambs—to name just a few. It's hard to imagine these characters existing in the real world, but Gein's actual crimes were so heinous that he might be the most monstrous figure in American history.

The Gein family wasn't exactly a Norman Rockwell portrait to begin with. His father, and two brothers passed away early in his life. After the passing of his sole companion, his beloved mother, Gein lived alone in their rural Wisconsin farmhouse, and the mild-mannered handyman didn't attract much attention in the 12 years following her death. But when a neighboring hardware store owner disappeared in 1957, Gein came under suspicion, and a search of his property revealed the decapitated woman in a shed, splayed out like a pre-skinned deer. Inside the house, authorities found masks, wastebaskets and lampshades made from human skin, along with assorted human remains. Some of what was discovered is far too grisly to mention here, but suffice it to say, Gein's living room would make Leatherface blush. It was later determined that he'd been making late-night visits to nearby cemeteries, exhuming women who looked like his mother—whose room was found boarded up and completely untouched. Gein's story, even sans chainsaw, is truly the stuff of nightmares.

The 2005 slasher pic Wolf Creek drew a lot of audiences with its "true story" tagline, but the movie bares only a vague similarity to the events that inspired it. The character of Mick Taylor, played by John Jarrat, is likely based on Australian serial murderer Ivan Milat. Milat, known as the "Backpacker Killer," savagely murdered at least seven young tourists in the mid-'90s, hiding their bodies in an outback forest. Medical examinations determined injuries ranged from 35 stab wounds in one corpse to nine shots in the head of another. Other wounds, including strangulations and beatings, were inflicted post-mortem. The head of one victim was never found.

Unfortunately for Milat, one of his would-be victims escaped. The young backpacker reported that Milat had lured him with false hospitality, tried to bind him with rope, and shot at him when he broke free. The tourist positively identified Milat, and he was eventually found guilty of all seven murders (and suspected of many others). He was sentenced to seven consecutive life sentences, plus 18 years. The trope of the meandering young tourists and the charismatic psychopath is nothing new, but the backdrop of the vast and remote outback makes for a pretty chilling story, proving again that fact can indeed be stranger—and scarier—than fiction.