These terrifying tales transpired off - camera on the set of your favourite cinematic nightmares .

If you’re ahorror moviefan, the phrase “based on a true story” is one you’ve probably heard over and over in conjunction with your favorite fright flicks.

But sometimes, the scariest stories associated with on-screen scare fare come from their respective sets, from macabre mishaps to chilling happenings that just can’t be explained.

With this in mind, I’ve assembled 18 true nightmares that you’ll be shocked to hear actually transpired behind-the-scenes of various horror films.

Ready? Here we go:

1.A catastrophic nightmare on-set ofA Nightmare on Elm Street, Part 4: The Dream Master:

2.Director Ti West’s unsettling experiences at the Yankee Pedlar Inn duringThe House of the DevilinspiredThe Innkeepers:

3.A creepy crawler nearly derailedSinister II:

4.IsThe Exorcista cursed film franchise? Many seem to believe so:

5.The truly ghastly incident on-set ofIncident in a Ghostland:

6.The horror of makingThe Texas Chain Saw Massacre:

7.And was there really a haunting on the set ofThe Possession? The evidence appears to point to yes:

8.Cost-cutting creepiness brought an eerie authenticity toPoltergeist:

9.Life imitated art on the set of theFriday the 13thremake:

10.The Amityville Horrorremake was plagued by creepy coincidences:

11.Bad omens raised hell on-set ofThe Omen:

12.Annabelle Comes Homehad a myriad of macabre mysteries:

13.Odd radio silence (or lack thereof) on-set ofThe Exorcism of Emily Rose:

14.The set ofThe Shiningmet a fiery demise:

15.They used real witchcraft for a fictional deity inThe Craft:

16.Wes Craven struck real fear into Miko Hughes on-set ofNew Nightmare:

17.Was there a ghostly presence on-set ofThe Lords of Salem? It sure sounds like it:

18.And finally — the cast and crew ofThe Pope’s Exorcistwitnessed a firsthand fright:

Text from the Trailer for "The Last House on the Left"

A production light blows out, revealing a creepy figure lurking in the shadows

A young boy screams as he records something terrifying on a handheld crank camera

A crying woman's face emerges from a fleshy wall covered in faces

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A blood covered woman leans against a large wooden door

A group of creepy children stand in a decrepit hallway

A man with a hat and briefcase basks in a light outside of a home at night

Two distressed young women embrace in a rustic home

A masked man with a chainsaw runs at a truck

A man holds an ornate Hebrew ceremonial box and device at his dinner table.

A woman pops up in a muddy pool of water next to multiple skeletons

A camera zooms in on the wet decrepit mask of Jason Voorhees

Lights blare from an upstairs room at the infamous Lutz House in Amityville

Gregory Peck and David Warner on the Set of "The Omen"

McKenna Grace prays in a dark, creepy room with 1960s decor.

A scared young woman stares down a dimly lit hallway

Jack Nicholson and Stanley Kubrick hang out by the monitor during the filming of "The Shining"

Four young women attempt to conjure magic on a beach

A demonic variation of Freddy Krueger poses menacingly.

A woman in creepy make-up and a long worn-out sweater stands in an ornate ballroom

Russell Crowe stares intensely as a demon-battling priest