With movie theaters beginning to reopen and films like The Unholy and The Conjuring: The Devil Made Me Do It set to premiere this summer, we’re taking a look at not the best, not the worst, but some of the scariest horror movies of all time (some spoilers may follow).

But what makes a movie scary? On this list, you’ll find films that have horrified audiences across decades. With standards of horror ever-changing in our increasingly tolerant society, it’s easy for one person to be scared by one thing and not another.

This list is going to dive deep into some of our most recent horror scares, as well as some of the classics. So don’t turn off the lights, here is our list of the 10 scariest horror movies out there…

1. The Exorcist (1973)

The original demon possession movie, The Exorcist, directed by William Friedkin, still frightens audiences today with iconic sequences of supernatural terror that most horror movies have failed to recapture since the film’s release. The Exorcist, based on the book by William Peter Blatty (who also wrote the screenplay), follows the demonic possession of a 12-year-old girl and the exorcism conducted by two Catholic priests, one of which is having serious doubts about his faith.

The Exorcist is most well-known for its various moments of terror including head twisting, levitating, spider-crawling, and various demonic voices as the demon Pazuzu terrorizes and possesses the young Reagan MacNeil (portrayed by the talented Linda Blair). The use of practical effects (such as the “stair dive” at the end), advanced puppetry, and the historic Georgetown help set the scene, making The Exorcist feel both aetherial and spiritual.

Less well known, however, is that the production was nearly a horror film itself, with the set burning down due to unknown circumstances and the seemingly random deaths of nine members of the cast and crew. To this day, The Exorcist remains one of the scariest horror films of all time and has led to various sequels, television series, books, and more. The film has become a phenomenon, securing its rightful place on our list.