I enjoyed Foucalt's Pendulum incredibly, it wasn't a light reading, but it was a very satisfying, fullfilling reading.

Andersen's tales are scary - those that outside of usual selection. The Marsh King's Daughter? Ouch! I still remember the feeling. My parents actually warned me before giving a book that it was going to be scary. But as a child I think, I wanted to read scary stories from time to time. It was some kind of controlled fear. I guess I am less likely to read dark stories now.