For a lot of horror fans, watching a film based on a true story makes their viewing experience all the more jarring. And really, we can’t argue with that. Taking in a reimagining of something that actually transpired is inherently more frightening than a film that isn’t grounded in reality. With that said, we’ve put together a guide to what we hold to be the ten most shocking films based on or inspired by actual events. We’ve ranked the films according to how shocking the movie is, how shocking the actual events are, and how closely the film follows the events it was based upon or inspired by.
#10 The Strangers
This film really struck a nerve with me the first time I saw it. Seeing The Strangers in a dark theatre, late at night really spooked me. Since the film relies heavily on jump scares and the viewers’ fear of the unknown, it’s not had the same effect in subsequent viewings. But, it certainly left an impression on me.
Writer/director Bryan Bertino loosely based The Strangers on details of the Manson murders that he picked up on while reading Helter Skelter. Bertino also drew influence from a series of break-ins that occurred in his neighborhood when he was a child. The burglars in the Bertino’s neighborhood would knock on doors and ask to speak to a person they knew did not live there. If no one answered the door, the group of hooligans would then burgler the home. Though, The Strangers is really based on a conglomerate of unrelated events, it still packs enough impact to earn the number 10 spot on our list.
#9 Wolf Creek
Wolf Creek is a terrifying film. When I first watched the film, not knowing just how closely the storyline followed the events that the film is based on, I was sufficiently terrified. The idea of a real life Mick Taylor still at large would be enough to keep me out of the Australian Outback indefinitely. However, it turns out that writer/director Greg Mclean relied pretty heavily on his imagination when penning the script for Wolf Creek.
It seems Wolf Creek is based on a couple of unrelated events, much in the way that The Strangers was. Wolf Creek is reportedly based on the abduction of a British tourist and his girlfriend. The tourist’s girlfriend was subsequently assaulted and the case later went to trial. The film also drew inspiration from the Australian Backpacker Murders. So, we have another case of a film that took multiple true-life events and merged them together. But ultimately, Wolf Creek is not based on any one person or event. The Mick Taylor character is a combination of different people with a bit of fiction thrown in the mix.
#8 The Texas Chainsaw Massacre
The Texas Chainsaw Massacre shocked impressionable audiences in 1974. And, causing viewers even greater discomfort was the fact that the film was marketed as being based on a true story. Even by today’s more permissive standards, a man murdering people with a chainsaw, while wearing a mask made of human skin is pretty shocking. I suspect that Gunnar Hansen’s iconic turn as Leatherface haunted more than a few audience members’ dreams back then.
The Texas Chainsaw Massacre took inspiration for the skin mask came from Ed Gein, as he was known to use human skin to upholster furniture and make clothing. But the chainsaw style murders and the backwoods inbred family element were not based on Gein’s life. Though, the film really only pulls a miniscule amount of inspiration from actual events, TCM is arguably the best grindhouse film of all time and is more than deserving of its spot at number 8 on our countdown.
#7 Psycho
Psycho was shocking not just for its violent content, but also because the story revolved around a man who would dress up in his deceased mother’s clothes. That was the type of thing most people would avoid talking about in 1960. But Alfred Hitchcock, being the filmmaking pioneer that he was made his movie, on his terms. Horror fans owe much gratitude to Hitchcock, as nearly every horror filmmaker to come after him lists Hitchcock as a major inspiration.
Psycho, which was adapted from the novel of the same name, is also loosely inspired by the life of Ed Gein. Gein was influential in the sculpting of the Norman Bates character. Gein was known to cross dress, which is referenced in Norman’s desire to dress as his dead mother. Though, very little of Psycho is actually based on true events, it earns its spot at number 7 on our list for being a pioneer in genre filmmaking and a shocking film for the time of its release.
#6 The Exorcism of Emily Rose
The Exorcism of Emily Rose is shocking for several reasons. Perhaps the most startling thing about the story is that Emily’s death may have been preventable. It is largely speculated that she was in fact suffering from several different medical conditions and not demonic possession.
Other than the changing of names and some editorializing, we see a pretty clear picture of what happened with Emily Rose (real name Anneliese Michel). Though, Emily Rose’s surviving family members were offended by the film and wanted nothing to do with it, the picture was true to the skeletal outline of Emily Rose’s story. A court ruled that Rose was not possessed, and believed that she was suffering from a series of medical conditions. But many people still maintain that Emily Rose was possessed and died a martyr. Emily Rose’s gravesite is now a place of pilgrimage for prayer.
#5 Open Water
One of a handful of contemporary films that actually scared me; Open Water plays so much on our fear of isolation and of losing control. In Open Water, we find a couple stranded in the middle of the ocean, taunted by the predatory animals of the sea. This film is not only shockingly effective it is terrifying. As a viewer, I constantly found myself thinking what it would be like to be stranded at sea with no hope of being discovered.
Open Water is based on the story of a couple that was separated from their party in a boating mishap. When the couple’s remains were found, there was no actual evidence of a shark attack. Though, the film takes some creative liberties with the content, what you see is a fictionalized account of actual events. The majority of the film is founded in reality, thus making watching it that much more intense. 
#4 The Amityville Horror
The story of the Lutz family is a positively frightening account of a family’s battle with malevolent spirits. Released in 1979, the film shocked audiences both for being based on a true story and for being relatively violent for the era in which it was released.
The Amityville Horror is still the source of much controversy. The film recounts experiences that the Lutz family claims to have had during the short time that they lived in the Amityville house. The film is based on a book detailing what happened to the Lutz family, while they occupied the home. Since there is very little hard evidence as to what actually happened, we can say that the film is a fairly accurate retelling of what the Lutz family says went on. However, Kathy Lutz came out, late in life, with a statement saying that the entire story behind her family’s stay in the home was fabricated for publicity. There are surviving members of the family who do not corroborate her claims. One key detractor is Daniel Lutz. His recollections of what happened in that house are detailed in the documentary My Amityville Horror. In the film, Daniel sticks to his guns, but does refuse to take a lie detector test.
#3 Henry: Portrait of a Serial Killer
Henry: Portrait of a Serial Killer is brutal, violent, and shocking all on its own, but knowing that the film is based primarily on actual events, and depicts real life serial killer Henry Lee Lucas makes it all the more chilling. Henry is a shocking film, in deed.
The film is a fictional dramatization of a period of time in Henry Lee Lucas’ life. So, while some of the details are changed, the core of the story is founded in truth. What makes Henry stand out is that where films like The Texas Chainsaw Massacre or Psycho have taken minor details about a real life killer and weaved them in to their story, the filmmakers responsible for Henry actually built an entire movie around Lucas’ life. Though some creative liberties were taken, the film sticks fairly close to the truth. Henry shocks the hell out of me every time I watch it and it rightfully earns the number 3 spot on our list.
#2 Compliance
Even if it weren’t based on actual events, we would hold Compliance as one of the most shocking films of the past five years. It’s the type of film that leaves the viewer feeling unclean and like an unwilling participant in the events he or she has just watched unfold. The fact that the film is based on actual events makes the viewing experience even more intense.
The truth behind the story is that between 1995 and 2004, a series of prank calls were placed to a variety of fast food restaurants. The calls were placed to restaurants in at least 30 U.S. States. The person behind the calls would pose as a police officer and asked for a restaurant employee to participate in various demeaning acts. Compliance focuses mainly on one such incident that took place in Mount Washington, KY. During the Mount Washington incident, the person claiming to be a police officer instructed the restaurant’s assistant store manager to perform a strip search on a young woman being accused of stealing a customer’s purse. The assistant manager’s fiancé was brought in for reinforcement and reportedly wound up sexually assaulting the young girl. Compliance appears to stick pretty close to the court records, though the film does take a couple of creative liberties.
#1 The Girl Next Door
The Girl Next Door is a highly intense film. I couldn’t shake it for days after I watched it. To think that people are inherently capable of the type of evil that plays out in The Girl Next Door shook me. I don’t foresee the desire to revisit The Girl Next Door again. It’s the kind of movie that watching it once is plenty.
In terms of staying true to the events the film was based on, there are very few discrepancies. The actual events took place in the 1960s, whereas the film version has the story unfolding in the 1950s. Also, the violence endured by the victims is not reported to be of a sexual nature, but was portrayed as such in the film. Beyond that, the film stays very close to the events on which it is based. For its unflinching approach to storytelling and faithfulness to the source material, The Girl Next Door lands the number 1 spot on our list.
Honorable mention to Silence of the Lambs, The Stepfather, and The Town That Dreaded Sundown