When horror movies are billed as "based on a true story" or the ever-popular "inspired by true events," it's usually done to simply elicit more audience interest. To put it bluntly, it's a marketing tactic used to get viewers in seats and eyes on screens. While some events and people portrayed might have occurred or existed at some point, it's a safe bet that most of the movie's material is highly exaggerated.

Some "true story" horror films do at least try to maintain the structure of their source material, but then there are those that go completely off the rails.

Updated on September 29, 2022 by Colin McCormick:

with the Halloween season approaching, many fans will be looking for great horror movies to enjoy during the spooky season. But while a scary story based on true events can make it all the more enticing, some of the supposed true stories certainly play it fast and loose with the facts. With a few more titles that fit the criteria of not-so-true horror movies, fans can delve into what really happened while also enjoying the Hollywood version.

The Exorcist (1973)

Fathers Karras and Merrin begin the exorcism in The Exorcist

Constantly noted as one of the scariest movies of all time, The Exorcist continues to hold up all these years later as a horror masterpiece. It tells the story of a young girl whose odd behavior soon intensifies until a pair of priests are brought in to help rid her of the demon who has possessed her.

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The movie is based on a novel by William Peter Blatty, which was itself inspired by events that took place in the 1940s with a young boy. While there are some unsettling similarities between the movie and the true story, the truly supernatural elements were all invented.

The Strangers (2008)

Three people wearing masks in The Strangers

While masked horror movie killers like Michael Myers and Jason Vorhees have become iconic, the villains in The Strangers deserve some recognition as well. These mostly silent assailants terrorize a couple in their isolated cabin for no apparent reason other than their own amusement.

The movie allegedly drew inspiration from a variety of senseless break-and-enter murders, including the infamous Manson Family murders of Sharon Tate and her friends. While it touches on the scary lack of reasoning being the crimes, there isn't a lot of similarities with that case.

Open Water (2003)

Susan swimming in Open Water

Shark attack movies have been a popular subgenre for horror fans ever since Jaws. Open Water takes a very realistic and eerie take on the genre as it follows a tourist couple on a diving expedition who are accidentally left behind in the middle of the ocean and are surrounded by sharks.

The details of a couple being forgotten on a diving expedition are inspired by true events and became the basis for the story. However, as the bodies were never recovered, the entire shark attack angle is completely hypothetical.

Tusk (2014)

Justin Long in Tusk

Though Kevin Smith is known for the more lighthearted View Askewniverse movies, he stepped into the horror genre with the bizarre Tusk. Justin Long plays a podcaster who interviews a reclusive man, only to be kidnaped by him and turned into a human walrus.

Kevin Smith became inspired to make the movie after finding out about a strange personal ad for someone offering free accommodations to anyone willing to dress up like a walrus and live with him. Not surprisingly, the ad was later proven to be a joke itself.

The Silence Of The Lambs (1991)

Hannibal Lecter and Dr. Chilton in Silence of the Lambs

The Silence of the Lambs stars Jodie Foster as FBI agent Clarice Starling who joins an investigation into a sadistic serial killer. In hopes of gaining insight into the murders, she seeks the help of incarcerated serial killer Hannibal Lecter, one of the most iconic movie villains of all time.

That one aspect of the movie is interestingly drawn from real events. In their investigation into catching the Green River Killer, the FBI spoke with serial killer Ted Bundy. However, the similarities between Bundy and Lecter as well as the rest of the investigation ends there.

Winchester (2008)

Helen Mirren featured in the poster for Winchester

Winchester isn't a perfect movie, not by a long shot. But that's not saying it isn't entertaining. It's an overly cliché haunted house film, but at least Helen Mirren gives an excellent performance as Sarah Winchester. And while it's the standard-issue haunting, the star of the production is the house itself.

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The Winchester Mystery House is responsible for inspiring several different fictional haunted houses, including the Hill House and even Disney's Haunted Mansion. Like the film, the property is full of winding corridors, doors that go nowhere, and other oddities, but it lacks the over-the-top CGI spirits.

The Serpent And The Rainbow (1988)

A coven performs voodoo in The Serpent and the Rainbow

While he'll always be known as the mind behind A Nightmare on Elm Street and Scream, Wes Craven also created a very underrated zombie film in the form of The Serpent and the Rainbow. But while viewers undoubtedly are swept up in its narrative of zombies and ancient Voodoo spells, it can be easy to forget that there is a true account hidden beneath the rites and rituals

Inspired by the book by Wade Davis, a scientist who investigated the zombification techniques seen in Haitian voodoo. The book itself is a dive into the world of black magic, psychedelic drugs, and other peculiar practices. Though the work was criticized for certain discrepancies, it laid the groundwork for a truly memorable horror film.

The Possession (2012)

A girl holds the Dybbuk Box in The Possession

The Possession is a bit more complicated when sifting through what's true and what was made up for the big screen, especially considering that the inspiration for the film came from more of an urban legend. The narrative of the possessed daughter was dramatized for the film, but the Dybbuk Box itself was a real artifact found at an estate sale.

The box was linked to several paranormal occurrences, and supposedly the death of one owner's mother. Its history and its mysterious contents have since made it the subject of many legends and supernatural/paranormal investigations.

The Conjuring (2013)

Lorraine holds a music box in The Conjuring (2013)

Thanks to the iconic Conjuring series, the names of Ed and Lorraine Warren have been pulled to the forefront of modern horror media. But while the investigations conducted by the pair of demonologists surround true supernatural phenomena, the movies they inspired are enormously over-the-top, scaring some fans right out of the theater.

True, the Warrens were a pair of real investigators (via USA Today), but the hauntings and manifestations they encountered were not entirely as visual or as violent. Apart from a few named entities such as Annabelle and Bathsheba, the spirits were mostly harmless. That being said, any form of haunting has its risks and its hazards.

The Birds (1963)

Crows gather on a jungle gym during the day in The Birds.

Alfred Hitchcock is a titan of horror, a fact that's pretty much common knowledge. Along with taking his viewers on a trip to the Bates Motel, Hitchcock also brought a swarm of ravenous birds to the screen that terrified audiences everywhere in the early '60s.

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By modern standards, The Birds is a bit far-fetched and over the top in its plot, spectacle, and presentation, but it was inspired by an actual occurrence that struck Monterey Beach (per ABC). While seagulls having seizures from contaminated plankton might not sound horror-movie-worthy, Hitchcock certainly ran all the way with the idea.

The Town That Dreaded Sundown (2014)

The Phantom Killer wears a burlap mask in The Town That Dreaded Sundown

The original 1970s feature The Town That Dreaded Sundown, inspired by the actual Texarkana Moonlight Murders (via Encyclopedia of Arkansas) stuck a little closer to the script than most, but its 2014 remake/sequel suffered from a mix of identity issues that pushed what was once something of a creepy, borderline exploitation film into a full-on gratuitous slasher film.

This meta-sequel slasher features a copycat murderer donning the Phantom Killer's mask and M.O. to create a sort of Texan alternative to Scream. It's violent, it's intense, but it's also somewhat dated and inflated to the point it becomes something completely disjointed.

The Amityville Horror (2005)

George Lutz under the rain in The Amytiville Horror

The original film based on the Amityville Murders is one of the most infamous haunted house stories ever told. With accounts of spiritual disturbances, demonic entities, and other forms of supernatural and paranormal activity, the terror of The Amityville Horror has lingered in the media for years.

Despite the original's reputation, the 2005 remake with Ryan Reynolds went completely over the edge and even ventured into silly territory with some of its visuals. Reynolds or not, it was a far cry from the horrors the '70s classic evoked.

The Texas Chainsaw Massacre (1974)

Leatherface holding chainsaw over his head in The Texas Chain Saw Massacre

Any slasher movie fan worth their salt will know that Norman Bates, Leatherface, and Buffalo Bill can all trace their existence back to Ed Gein, the infamous "Butcher of Plainfield." That being said, most movies inspired by his acts of horror are almost all greatly exaggerated, especially Tobe Hooper's 1974 splatter fest.

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While it is true that Gein did have masks, furniture, and other things made from human flesh, he didn't go chasing a group of hippies through his farmhouse. Leatherface was simply a gross embellishment created to sell tickets and build a franchise.

Misery (1991)

Annie Wilkes holding a knife in Misery.

With a villain who is not supernatural or a monster, Misery is a simple yet effective horror movie. Stephen King's Annie Wilkes comes from a strange place, both real and fictional. The character of Annie herself is supposedly inspired by a real-life murderous nurse named Genene Jones (per CBR), but the book and film as a whole both sprout from a source that hits a little closer to home for the prolific author.

While a more metaphorical horror story than the one it inspired, Misery drew its existence from the author's struggle with addiction and an unforgiving fanbase. Similar to how Annie kept Paul Sheldon a prisoner until he wrote another bestseller, King was a prisoner to a very vocal fanbase after writing Eyes Of The Dragon as well as dealing with his dependence on drugs and alcohol.

Cannibal! The Musical (1993)

Four cast members as they appeared in Cannibal The Musical

A musical inspired by the infamous Alferd Packer (via Colorado Virtual Library) written by the creators of South Park already sounds like something completely out of Parker and Stone's animated series, but it was Trey Parker's film debut before he and Matt Stone made the successful transition to South Park. It's a horror movie inspired by a true historical figure, but it goes above and beyond on the campy and kitschy over-the-top nature.

Cooks who wield katanas, song-and-dance numbers about snowmen, and even a cyclops are just a few of the strange and unusual elements that go into this incredibly unusual musical. It might not keep many viewers up at night, but it does have something of a cult following, and it even received its own Off-Broadway adaptation in 2001.

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