A number of well-known horror films are based on actual events.
1999's Ravenous, for example, was inspired by the activities of Alfred Packer in the 1870s while A Nightmare On Elm Street had its roots in the "Asian Death Syndrome" affecting Khmer refugees in the 1970s.
Elsewhere, David Cronenberg's Dead Ringers was inspired by the careers and demise of identical twin gynaecologists Stewart and Cyril Marcus who practiced at New York Hospital and Cornell University Medical College. The pair died together in 1975, the result of drug withdrawal following prolonged and extensive use of barbiturates.
And most will know about The Texas Chainsaw Massacre. Tobe Hooper’s seminal 1974 horror film is entirely fictional. However, Leatherface and the psychotic family who attack and mutilate a group of innocent people have motivations and modus operandi mimicking that of notorious mad man Ed Gein.
The Mad Butcher was arrested following investigations into the disappearance of shop owner Bernice Worden in late 1957. The woman’s body was found at Gein’s home, her head missing. It was here that investigators also found human remains which had been fashioned into furniture such as a wastebasket made out of human skin and bowls made from skulls. The Texan native was found to have murdered at least two people while exhuming a number of recently buried bodies to make various domestic items.
See Top 10 Films' list of the best horror films based on a true story here.