10 Horror Movies So Sad You Can Only Watch Them Once

In I Saw the Devil, secret agent Soo-hyun discovers his pregnant daughter has been raped, murdered, and dismembered by deranged psychopath, Jang. Blinded by revenge, Soo-hyun promises to hunt down and kill this maniac.

I Saw the Devil is, without doubt, one of the best horror films to come out of South Korea. And yet, you'll struggle to find anyone who's seen it more than once.

Is it because of the violence and gore? Absolutely. But another reason why I Saw the Devil is a hard watch is Jang. Not only does he mutilate his victims beyond recognition, he takes such gleeful pleasure in doing so. Rarely in cinema have we seen a villain so utterly remorseful of his barbaric urges. You can see in Jang's eyes that he feels true bliss, knowing his actions destroy the lives of his victims and their families. Jang may get his comeuppance in the most horrific way possible, but it brings us no joy, knowing the pain he's brought to the world.

Also, I Saw the Devil is a long movie. After you've seen Jang commit atrocity after atrocity throughout the 148-minute run-time, there's a point where you think to yourself, "I'm never watching this again."