IT by Stephen King scared the fucking bejeezus out of me.

And the Otherland series by Tad Williams is super creepy and awesome.

Sorry, if I'm going to be arsed to read 1000 pages, it ain't gonna be Stephen King.

House of Leaves spooked me pretty good; non-euclidian geometry usually does it for me.

Yeah, the Scary Stories books always fascinated me/creeped me out as a kid--but I think this was due more to the illustrations than the text:

http://www.comicsalliance.com/2010/10/25/s…

And yes to what catandbeard said: The only book in even semi-recent memory that I remember genuinely freaking me out was House of Leaves.

Misery by Stephen King!

I don't remember the title, but I remember my mother reading a book so scary she threw it down and couldn't finish it. The opening line was something like "It was the devil's summer in the South, and the air was filled with the smell of burning children."

Scary Stories was awesome and I vividly remember that I couldn't even peek at the page of the ghost woman emerging from a bedroom to find the person who stole the silver coins off of her dead eyes.

I read a bunch of King when I was a kid, and Pet Sematary did it for me. Also, many of the short stories in Night Shift.

The illustrations in Scary Stories were horrifying when I was a kid; still are, really.

Pet Sematary freaked me out when I was in fourth or fifth grade. Scared my mom even worse when I came up to her with the book and asked what "cunt" means. And the description of Zelda? Sheeeit.

The Holy Bible! Get it? Because Christians are sooooooooooo stupid (sarcasm!)

When I was a kid, we had these really short illustrated kid's Time Life books about all sorts of shit-- loch ness monster, UFOs, Atlantis, bigfoot and, of course, there were "Ghouls and Ghosts" and "This House is Haunted!" The illustrations especially really spooked me.

I'm reading "The Strain" right now, not super scary but creepy and good so far.

Scary Stories, definitely, but that had everything to do with the illustrations.

As a kid I also loved John Bellairs' books, particularly the editions with the Edward Gorey covers. 'Salem's Lot also freaked me out when I read it in sixth grade.

The freakiest stuff, though, had to be Robert Cormier's books, particularly The Chocolate War. His stuff doesn't have any ghosts or demons or whatever in it- it will just convince your adolescent mind that the world is horrible, people are generally bad, and that we are all, in a broad sense, kind of fucked in the end.

@Joe TOTALLY. I reread I Am the Cheese a couple years ago and was kind of shocked by how dark it was.

Also, Christopher Pike's Whisper of Death. I learned the word "hemorrhaging" from that book!

I was talking to my roommate about this very topic yesterday—neither of us could think of books that, as adults, have genuinely scared us. (And we both got a little terrified while rewatching Veronica Mars last night, to give you some idea of how very low the scare bar is.)

Anytime I read H.P. Lovecraft, I have to turn on every light in the apartment.

"Low Red Moon" by Caitlin Kiernan is a good 'un. "Dark Harvest" by Norman Partridge.

@Joe I can't believe I forgot about John Bellairs. Those books had the coolest titles too. I remember in Eyes of the Killer Robot, there was the ghost with no eyes who kept moaning, "They tooooook my eeyeees." Freaked me out.

Harry Clarke's illustrations for Poe's Tales of Mystery and Imagination did it for me.

I've been reading some HP Lovecraft this season. Surprised that it has given me psuedo-nightmares a couple of times.

Orwell's 1984 is pretty damned scary. I first read it when I was 11...perhaps a bit too young. But it still scares me. Supernatural stuff has never scared me much, maybe because I don't believe in any of it. Trying my hand at writing horror fiction in the '90s took more of the scare out...once you're working with the nuts and bolts, there isn't as much mystery. The human capacity for cruelty can scare the hell out of me, though.

The House With A Clock In It's Walls by Bellairs. My favorite book as a kid. More frightening and suspensfully real than other-wordly. I can still remember character details many, many years later, and how much I related to and liked them. Just ordered it, too! Can't wait to read it again.