Some of the best horror movies are actually based on true stories, and that makes them all the more frightening. Horror and cinema go together perfectly, and some of the most memorable films from each era have come from the horror genre. From creepy monsters to ᴅᴇᴀᴅly killers, horror movies are always dreaming up new ways to mortify viewers.

One of the easiest ways to add some extra chills is to slap on the tagline “Based on a True Story”. While the veracity of that claim has been stretched to its absolute limit over the past half-century, even a kernel of truth can have audiences flocking to the theater in droves.

It’s no secret that horror filmmakers draw inspiration from real life, and those stories inevitably find their way onto the big screen. Gruesome true crime cases, supposed hauntings, and everything in between is fair game in the world of horror. Sometimes, those movies are elevated beyond mere scares, and become bona fide classics that transcend the genre.

The Sacrament (2013)

A few years before the debut of his X trilogy, Ti West delivered one of the most nightmarish found footage horror films of all time. The Sacrament is based on the events of the 1978 Jonestown Mᴀssacre, and it borrows liberally from many of the more horrifying details of the case.

It wasn’t the first movie based on Jonestown, but it’s the only one to do it justice as a horror story. The found footage elements are superb, and it mimics the way the public witnessed the actual event. Though excellent, The Sacrament loses points to other “True Story” movies because it is a bit too literal in its adaptation.

Open Water (2003)

The true story of Tom and Eileen Lonergan captured the imagination of news viewers in the late 1990s, and it made for an effective survival horror story in 2003’s Open Water. Unlike other shark attack movies which pit the heroes against an almost supernatural aquatic monster, Open Water is slow-paced and dour.

Because there is little known about the final moments of the Lonergan’s lives, Open Water is almost entirely fictional. However, the filmmakers opted not to go too extreme, and that makes the movie even scarier in an intellectual sense. The indie success lacks traditional scares, which has made it a divisive horror flick in the years since.

Henry: Portrait Of A Serial Killer (1986)

Some horror movies based on serial killer cases are guilty of being too salacious and cynical, but Henry: Portrait of a Serial Killer strikes a fine balance. The ultra-low-budget shocker is very loosely taken from the (questionable) confessions of serial killers Henry Lee Lucas and Otis Toole, but there is no cinematic gloss to cover up the pure terror.

Michael Rooker gives a career-defining performance as Henry, and the movie isn’t a slasher film, but instead lives up to its тιтle by being a gory character study. It’s a dissection of the motivations of murder, and it also takes jabs at the celebrity of crime. However, it’s almost too upsetting for its own good, and is a tough rewatch.

Poltergeist (1982)

Poltergeist is one of the most beloved ghost movies, and it actually is very loosely based on a story from the 1950s. Taking mᴀssive creative liberties, the Tobe Hooper-directed classic was inspired by the Hermann family’s supposed haunting in Long Island, New York. Though the real case was somewhat mundane, the movie added a lot more to spice things up.

Spooky yet accessible, Poltergeist has a whimsical style that makes the ghosts ethereal and fun. The movie’s cursed reputation adds another layer of chills, and it’s a highlight of the distinct ’80s horror variety. Though a better film than most, Poltergeist‘s distance from its source material does knock it down a peg.

The Conjuring (2013)

Ripped straight from the case files of supernatural experts Ed and Lorraine Warren, The Conjuring helped usher in a new era of horror films in the early 2010s. Though the veracity of the movie’s claims are certainly suspect, The Conjuring does an excellent job of building up suspense by slowly meting out the scares as things build toward the climax.

It takes necessary creative license to deliver an effective horror movie, but never goes off the rails. The greatest success of The Conjuring is how it sets up a larger universe, and it keeps viewers engaged by teasing other haunts. Even if the story turned out to be total fiction, it’s such a great film that it doesn’t really matter.

Scream (1996)

Screenwriter Kevin Williamson penned Scream as a meta commentary about the horror genre, but he added a dash of true crime as well. Ghostface’s rampage is tenuously based on the Gainesville Ripper killings of Danny Rolling, who was allegedly inspired by horror movies he had seen. The movie builds from there, and borrows no actual details from the case.

In a decade that struggled to find its horror idenтιтy, Scream was the perfect way to put the ’80s slasher boom to rest. Besides all of its insightful commentary about horror, Scream is also just a well-made movie all around. Williamson took the essence of the Gainesville Ripper case, and managed to cull clever themes from the tragedy.

The Silence Of The Lambs (1991)

No case captured the imagination of Hollywood quite like that of Ed Gein, and The Silence of the Lambs was the third major film to borrow from the ’50s nightmare. Serial killer Buffalo Bill is another classic villain to spawn from Gein’s crimes, and the story dives into his motivations in a way that previous movies hadn’t.

No thriller film before or since has blended so well with horror, and The Silence of the Lambs is scarier than most pure horror movies. The multi-Oscar winner has a cinematic quality that elevates it above its genre, and it approaches true crime from a mostly realistic standpoint. Its realism is ultimately what makes it such a nightmarish ride.

Psycho (1960)

Alfred Hitchcock took a very dark turn when he directed Psycho, and the film began a new chapter of horror history in the early ’60s. Released just a few years after Ed Gein was apprehended, Psycho adapted the Robert Bloch novel, which fictionalized the crimes of Gein using the information that was available at the time.

Psycho successfully obfuscated most of the grizzly details from the Gein case, and boiled them down in a way that was acceptable for 1960. The movie was shocking, but Hitchcock’s deft touch kept things classy. Its best elements have almost nothing to do with its true crime inspiration, but its groundbreaking story is enough to cement it in horror history.

The Texas Chainsaw Mᴀssacre (1974)

If Psycho tiptoed around the most stomach-churning aspects of the Ed Gein case, The Texas Chainsaw Mᴀssacre highlighted them. Playing up every rumored or true detail, Tobe Hooper’s grindhouse classic was a direct response to the real-life terrors that the world has seen since Gein’s spree. The Vietnam War had shattered the American Dream in the 1970s.

Leatherface instantly became a horror icon, and the movie’s gritty low-budget execution made it look almost like a documentary. It’s impossible to overstate the importance of The Texas Chainsaw Mᴀssacre, and it pushed horror to gruesome new heights. It’s also one of the first movies to claim to be “Based on a True Story”, a gimmick that still works today.

The Exorcist (1973)

The Exorcist is generally considered the scariest movie of all time, and it’s even scarier because it was based on a real-life incident. Author William Peter Blatty drew inspiration from the exorcism of Roland Doe in the 1940s, though he embellished almost all the details to make a more compelling story.

The movie helped popularize exorcism, and began decades of Satanic panic. The actual exorcism is the subject of much debate, but The Exorcist is scary because of its realistic detail, not its connection to a true story. The Exorcist chilled viewers to the bone, and also became the first horror movie to score a Best Picture nomination at the Oscars.