Your favorite horror movie was a much scarier true story

“The Texas Chain Saw Massacre” (1974)

By Hank Sanders

We’re in the Spooky Season. Halloween costume shops have taken over vacant buildings; “Monster Mash” is on our playlists; and, best of all, horror flicks are waiting to be watched.

When we terrify ourselves with scary movies, we calm back down with the reminder: It’s not real, it’s not real, it’s not real.

Except ... when it is.

Some of the most popular movies in the genre are based, with varying accuracy, on true stories. In many cases, the real story is even scarier than Hollywood’s rendition.

(Spoiler alerts galore.)

‘The Exorcist’ (1973)

Green porridge vomit and ’70s makeup production are slightly less frightening than they were in 1973, when audience members fainted during screenings of “The Exorcist.” But the film’s origin story is just as terrifying.

In 1949, a couple living in the Washington, D.C., area noticed that their 14-year-old son was behaving strangely. Robbie, a pseudonym used in news coverage, recited Latin phrases, despite never having learned the language, and had strange etchings on his body; his bed and other items around him shook or moved inexplicably, The Washington Post wrote.

Believing Robbie had been possessed by a demon, the family traveled to St. Louis and sought help from Jesuit pastors at St. Louis University. One of them, the Rev. William Bowdern, would conduct a 35-day-long exorcism that was widely covered by news organizations.

Unlike in the film, which won two Oscars, there was no head spinning or floating involved, said Henry Ansgar Kelly, a professor at UCLA who interviewed Bowdern in 1960. In the film, it was a young girl instead of a boy, and Washington instead of St. Louis.

But there were some similarities: The priests involved have said they witnessed Robbie’s bed shake and move across the room.

Bowdern also told Kelly he saw scratch marks on Robbie’s chest that spelled “HELL.”

Interviews with people involved in Robbie’s exorcism became the basis for the book and the movie. When “The Exorcist” was filmed on Georgetown University’s campus, the set was so rife with accidents — a carpenter lost multiple fingers, and the set mysteriously caught fire — that a Jesuit pastor had to bless it several times.

‘Devil’s Pass’ (2013)

Weeks after they set out on a hike in Russia’s Ural Mountains, a group of nine people was found dead in 1959 in mysterious circumstances.

A search-and-rescue team found their bodies hundreds of yards from their tent — “some barefoot and almost naked” — in an area that was later named Dyatlov Pass after the troop’s leader, Igor Dyatlov, a 23-year-old engineering student, The New York Times reported.

Unexplained radiation was found on some of the clothes. One woman was missing her tongue, while others suffered blunt-force injuries.

“Why would nine highly experienced hikers leave a perfectly good tent, insufficiently clothed, in subzero conditions and walk a mile to their certain death?” said Donnie Eichar, the author of “Dead Mountain: The Untold True Story of the Dyatlov Pass Incident.”

In the movie “Devil’s Pass,” the answer is that the hikers stumbled upon a secret bunker where the Russian government was testing teleportation technology.

The reality remains complicated: Russian officials have said the deaths resulted from an avalanche. Eichar theorized that it was a swirling wind movement called Karman vortex streets.

“It’s the middle of the night. They were sleeping. They were insufficiently clothed,” Eichar said. “It was a fight-or-flight situation.”

But with no surviving witnesses, questions may remain unanswered.

“Devil’s Pass” (2013)

‘The Texas Chain Saw Massacre’ (1974)

The movie considered seminal to the slasher genre features disturbing scenes such as a man cutting people open with a chain saw and a victim pierced with a meat hook.

Kim Henkel, one of its creators, told Texas Monthly in 2004 that he had studied the cases of Elmer Wayne Henley, a 17-year-old accomplice to Houston serial killer Dean Corll, 33, and another killer, Ed Gein, to develop the film.

Henley, the accomplice to Corll, who was believed to have killed at least 27 people, fatally shot Corll in 1973 and then led police to a storage shed where bodies were found. He also confessed his own role in some of the murders and is serving life in prison.

“This kind of moral schizophrenia is something I tried to build into the characters,” he told Texas Monthly.

Gein, who confessed to killing two women in Wisconsin in the 1950s and making furniture out of human skin, among other disturbing events, was also the inspiration for Alfred Hitchcock’s “Psycho.”

‘The Amityville Horror’ (1979)

In December 1975, when the Lutz family moved into a beautiful, five-bedroom home with a swimming pool in the Amityville area of Long Island, the $80,000 price tag seemed like a steal.

“It was a dream come true,” George Lutz told ABC News in 2002.

But the family later learned the reason for the amazing price: Ronald DeFeo had killed six members of his family in that home the year before.

Four weeks after the Lutz family moved in, they “abandoned the house” after one too many paranormal experiences, according to “The Amityville Horror,” a 1977 book by Jay Anson about the family’s time in the home. Strange voices filled the home, and Lutz’s wife was said to be lifted off her feet.

The book and subsequent film adaptations were not totally accurate, Lutz later said. He even sued the 2005 film’s producers for defamation.

‘The Lighthouse’ (2019)

Watch Willem Dafoe and Robert Pattinson spiral into insanity as they tend to a lighthouse on a mysterious island.

The movie was based on an event known as the Smalls Lighthouse Tragedy.

In 1801, Thomas Howell and Thomas Griffith were hired to tend to the lighthouse on Smalls Island, a tiny scab of rock about 18 miles off the western coast of Wales, Julian Whitewright, a maritime archaeologist in Wales, said in an interview.

But Griffith died suddenly of an illness, according to Stephen Liddell, a tour guide and historian. In such a remote area, Howell had to keep Griffith’s body in his living quarters until the next shift of lighthouse keepers could arrive.

But storms delayed reinforcements, and Howell was stuck alone with Griffith’s deteriorating body, slowly going insane. Howell eventually tied it to the railings along the exterior of the lighthouse, where it stayed for four months until relief finally arrived, Liddell said.

Director Robert Eggers’ version of the tale, “The Lighthouse,” took creative license and was more of a psychological, slow-burn thriller.