4. The Hills Have Eyes
Here's where things start getting truly ridiculous. Wes Craven's 1977 exploitation horror classic The Hills Have Eyes features mutants and brutal murder in the desert, but all of this is centered around some measure of events that actually happened - the reign of the Sawney Bean Clan. The Clan existed in late 15th century and early 16th century Scotland, and Bean, along with his wife, lived on the coast with their 14 kids, attacking passers-by and then cannibalising their remains. Naturally, suspicions soon arose - especially after body parts began washing up along the shore - and the Bean family were apprehended. At the time of their capture, there were 48 members of the clan, the vast majority of them being the product of incest, and after it was found at trial that they had probably murdered over 1000 people, every single one of them was put to death. Like The Texas Chainsaw Massacre, it's arguably even more disturbing than Craven's tale, and I have to say, having researched this story, I would definitely watch a movie if they made a faithful adaptation of it.