What are some really scary stories?

Answer 1

For adults: the short stories of Clive Barker are some of my personal favorites. Try Books of Blood, Volumes 1 and 2.

For kids: when I was growing up, my favorite scary stories books were the Scary Stories books by Alvin Schwartz, illustrated by Stephen Gammell. There are three of them, plus the anthology: Scary Stories to Tell in the Dark, More Scary Stories to Tell in the Dark, Scary Stories 3: More Tales to Chill Your Bones, and The Scary Stories Treasury: Three Books to Chill Your Bones.

I also loved the Tales for the Midnight Hour books by J.B. (Judith Bauer) Stamper: Tales for the Midnight Hour, More Tales for the Midnight Hour, Still More Tales for the Midnight Hour, and Even More Tales for the Midnight Hour.