#5 The Shining by Stephen King
The book is so much scarier than the movie! Why? Because the characters are so real, the dialogue so dang familiar, you really go there and get sucked into the madness.
#4 The Exorcist by William Peter Blatty
I read it under my desk in 6th grade -- parochial school, no less, where we were taught to live in fear of the devil, the world, and our own sinful flesh. I was terrified for weeks, and 30something years later, I still haven't found the courage to see the movie or revisit the book.
#3 Rebecca by Daphne Du Maurier
The Grandmama of all Gothics. Spine-tingling, beautifully written, intricately plotted, and an education for writers. Time, place, storytelling, world-building, characters -- it's all there.
Wuthering Heights (Norton Critical Editions) by Emily Bronte
My first Bronte, and it scared the living you-know-what out of me the first time I read it. Unfortunately for my sister Jas, this was when we were still sharing a room, and I woke up screaming more than once. (We had lilacs outside our bedroom window, and -- well, it could have easily been a wraith! C'mon!) This Norton Critical Edition traces changes in the text since the book was originally published in 1847. Fascinating for writerly readers. And the chick clawing at the window is still dead scary.
#1 In Cold Blood by Truman Capote
Nothing terrifies me more than the human capacity for cruelty. This book is psycho-thriller, slasher flick, true crime, campy irony, and gut-wrenching human drama all in one. As Truman Capote himself predicted, it changed the way books are written -- both fiction and nonfiction. This masterwork is both an education and a cautionary tale for writers. Prepare to sleep with the lights on.