This book series was absolutely terrifying as a child, and still holds up as terrifying today. These were the type of stories to give you nightmares, and the illustrations were just as scary as the stories themselves.
I remember I collected these in grade school, and my friends and I would pass them around as soon as we got a new one. I'm almost positive I owned every Joan Lowery Nixon mystery at one point before eighth grade. These YA mysteries were full-on scary, featuring everything from the paranormal to all-too-human killers.
Once I read my first Christopher Pike, I was hooked. I would grab every one I could find at yard sales and used book stores and immediately devour them. They were like the gateway to "grownup" scary books, playing on a lot of the same themes of books I read now.
What were your favorite scary reads when you were a kid, or teenager?