But there's a special sub-genre of horror films that are extra goosebump-inducing and those are scary movies based on true stories. While any movie about a psycho killer is freaky enough, what makes a character like Ghostface in Scream is the fact that he's based on a real-life killer.
These four scary movies are each based on a true story that will haunt your dreams.
So in honor of all the most terrifying scary movies that we're too afraid to watch alone because they're based on true stories, here is a list of horrifying scary movies and the gruesome events that inspired them.
Psycho is an Alfred Hitchcock suspense classic that shocked audience members when it came out. In it, a young woman is murdered in her motel shower — perhaps one of horror's most classic scenes — which leads audiences into an investigation regarding the creepy motel owner, Norman Bates, and his domineering mother.
Psycho was adapted from a 1959 book by the same name, which was loosely based on the exploits of serial murderer Ed Gein, who also had a fixation on his mother and committed brutal murders in the '40s and '50s. Horror-movie aficionados may also recognize Gein as the inspiration behind Texas Chainsaw Massacre's Leatherface and the killer that Jodie Foster's character is trying to catch in Silence of the Lambs.
Scream was the slasher classic of the 1990s. In fact, the 1996 original was such a hit that it led to a four-movie franchise. But in the movie that started the hype, four high school friends have to escape a killer called Ghostface who wants them dead for an unknown reason.
Fans of the movie (and anyone alive during the '90s) will immediately recognize the creepy Scream mask popularized by the movie, which still inspires plenty of nightmares. But what's even scarier is the fact that the movie was based on a real-life serial killer: the Gainesville Ripper.
This notorious killer wreaked havoc at the University of Florida in August of 1990, when he broke into the home of two young freshmen and began a killing spree that forced the university to cancel classes for a week. Luckily, he was caught soon after, but Scream has also inspired a bunch of senseless masked murders since its release.
The Hills Have Eyes (1977)
The Hills Have Eyes is directed by horror pioneer Wes Craven, and it's about a vacationing family who gets stranded in a desert and falls prey to a pack of blood-thirsty cannibals.
While the premise sounds stranger than fiction, this story is based on the real-life Sawney Bean Cave Clan of Scotland, who were a group of cannibals that killed over 1,000 people in the 16th century.
The clan would target travelers, rob them, and eat them — until one man got away and alerted authorities. The story of the Sawney Bean Cave Clan has inspired countless plays and novels, in addition to this film, which was remade in 2006.
The infamous Zodiac Killer has inspired a number of movies, including Zodiac, which stars Jake Gyllenhaal as Robert Graysmith, a political cartoonist with the San Francisco Chronicle who was instrumental in attempting to decode the killer's cryptic messages.
The original Zodiac Killer terrorized the San Francisco Bay Area during his killing spree, which stretched from the '60s to the '70s. During the investigation, the killer famously sent the police and media letters, bloodstained clothing, and other taunting pieces of "evidence" to supposedly help them catch him.
What makes the Zodiac Killer an enduring source of terror today is the fact that the real killer was never caught. Plus, given the fact that he was active in the 1970s, he may well be alive today.
Until he's caught, remember to lock your doors at night. And maybe catch a couple of these real-life inspired horror movies, so you don't make the same mistakes the victims did.