While most, if not all, horror movies include a fair amount of fiction to make the story more gory and gruesome, often times the inspiration for these classic horror movies are based on true stories. The actual events in a lot of cases are that of legend or not nearly as scary as the theatrical version, but every so often the true events are scarier than anything someone could think up for shock value.

Some of the very best horror movies of all time are based on actual events. Take "Psycho," "The Texas Chainsaw Massacre" and "Silence of the Lambs," for example, three of the scariest horror movies of all time are based on the horrible killings of a single man, Ed Gein. Independently, the three films tell horrifying tales of mass murder, torture and cannibalism but put them all together and you get a look at serial killer Ed Gein.

Of course in many cases, the fiction is a stretch on the actual facts such as in the haunted house horror films. In "The Amityville Horror," "The Haunting in Connecticut" and "The Entity," families were haunted by demons in their own homes. In reality, investigators dispute many of these claims with some declared straight up hoaxes.

Good luck trying to verify claims of demon possession, which is another theme in some of the most well-known horror movies as well like "The Exorcist," "Audrey Rose" and "The Exorcism of Emily Rose," as those stories visit a gray area between paranormal and simple mental illness.

However these films were inspired, be them gruesome true events or a simple unverified claim that grows into a scary screenplay, these horror movies based on true stories all accomplish what they attempt to do, scare the crap out of us on a daily basis. For that, mission accomplished.
    
1.1The Amityville Horror

1.2The Exorcist

1.3The Hills Have Eyes

1.4 Jaws

1.5The Haunting in Connecticut

1.6Audrey Rose

1.7The Exorcism of Emily Rose

1.8The Serpent and the Rainbow

1.9The Mothman Prophecies

1.10Henry: Portrait of a Serial Killer

1.11The Entity

1.12Dead Ringers

1.13Ed Gein: Inspiration for Many Classic Horror Movies