5 . The Amityville Horror

Premise: A young family moves into a house where a murder was committed, and experiences strange and terrifying occurrences.

Real-Life Inspiration: Based on the book of the same name, The Amityville Horror follows the paranormal events that terrorized the Lutz family. In 1975, the family moved into 112 Ocean Avenue where, unbeknownst to them, Ronald DeFeo, Jr. had brutally murdered his family 13 months before they arrived. While in their new home, the family claimed that they saw green slime on the walls and red-eyed pigs staring into their kitchen and living room. After less than a month, the Lutz family moved out of the small town of Amityville, New York.

4. Psycho

Premise: A secretary goes on the run after she steals $40,000, only to wind up in a motel where the innkeeper and his mother are more than they appear to be.

Real-Life Inspiration: Psycho's Norman Bates is loosely based on convicted murderer and grave robber Ed Gein, who, during the late 1950s, killed women and unearthed corpses in Wisconsin. He also fashioned human skin into tiny keepsakes and knickknacks, such as face masks, belts, and chair coverings. Psycho's novelist Robert Bloch based Bates on Gein, but changed the character from a grave robber and murderer into a serial killer who dressed like his mother. The Texas Chainsaw Massacre and The Silence of the Lambs also based their serial killers—Leatherface and Buffalo Bill, respectively—on Gein.

3. The Exorcist

Premise: Two Catholic priests perform an exorcism on a young girl who is possessed by the devil.

Real-Life Inspiration: The Exorcist's author and screenwriter William Peter Blatty based the novel and film on a Washington Post article from 1949 headlined, "Priest Frees Mt. Rainier Boy Reported Held in Devil's Grip." The article followed Jesuit priests William S. Bowdern, Edward Hughes, Raymond J. Bishop, and Walter H. Halloran participating in the rite of exorcism on a boy with the pseudonym "Roland Doe" in Maryland. According to the priests, they allegedly experienced the boy speaking in tongues, the bed shaking and hovering, and objects flying around during the ordeal. The exorcism was one of three official Catholic Church-sanctioned exorcisms in the United States at the time.

"Maybe one day they’ll discover the cause of what happened to that young man, but back then, it was only curable by an exorcism," William Friedkin, the director of The Exorcist, told Time Out. "His family weren’t even Catholics, they were Lutheran. They started with doctors and then psychiatrists and then psychologists and then they went to their minister who couldn’t help them. And they wound up with the Catholic church. The Washington Post article says that the boy was possessed and exorcised. That’s pretty out on a limb for a national newspaper to put on its front page ... But you’re not going to see that on the front page of an intelligent newspaper unless there’s something there."

2. The Girl Next Door

Premise: An aunt tortures and abuses her niece, and a neighborhood boy fails to alert the authorities.

Real-Life Inspiration: Based on Jack Ketchum's novel of the same name, The Girl Next Door is based on the murder of Sylvia Likens, a 16-year-old girl from Indiana in 1965. Sylvia and her sister Jenny were left in the care of Gertrude Baniszewski, a family friend, when their parents left town as traveling carnival workers. Baniszewski, along with her children and a few neighborhood kids, locked Sylvia in the basement, where they tortured and abused her until she died of a brain hemorrhage and malnutrition.

1. The Conjuring

Premise: Two paranormal investigators help a family who move into a secluded home plagued by weird events.

Real-Life Inspiration: The Conjuring is based on real-life paranormal investigators Ed and Lorraine Warren and their experience with the Perrons, a family who moved into a Rhode Island farmhouse and experienced ghostly and terrifying occurrences in 1971.

"When Insidious came out and was successful the story about the Warrens came to me and I was like, 'Oh, my gosh, this is really cool,'” director James Wan told Entertainment Weekly in 2013. "But I didn’t just want to make another ghost story or another supernatural film. One thing I had never explored was the chance to tell a story that’s based on real-life characters, real-life people. So those were the things that led me to The Conjuring."

The Warrens also had a possessed Raggedy Ann doll that was the inspiration for the spin-off film Annabelle. Allegedly, a demon spirit possessed the Raggedy Ann doll, which is currently on display and under lock and key at the Warrens' Occult Museum in Monroe, Connecticut.