Man, it's really hard to pick just one, but I'd probably have to go with The Exorcist. And some of those sequels are damn good, too. Not the second one, but the third-where that serial killer is locked in the hospital and is sharing a body with the priest that saved Reagan in the first one. Creepy ending!

I also love Halloween (surprised no one mentioned it), Texas Chainsaw Massacre (original, and ONLY that), and the Blair Witch. I think I like Blair Witch so much is because it's not acting. It's real. What a great idea the producers had: find 3 random actors, set them up in the woods, and scare the shit out of them and film their reactions. It's very emotional which adds to the realism, plus it's creepy.

Basically any horror movie made from 1995ish and on is SHIT. Pure shit. All the great films were made way back in the day. This popular culture bullshit that's out now makes me sick. Saw 3, newer shit versions of texas chainsaw...pshh..come on. ~