Disturbing Books ?

What would you name as the most disturbing books you've read..

For me it'd have to : Anything by Peter Sotos, De Sade, American Psycho by Bret Easton Ellis



 What about you ?

Survivor, by Chuck Palahniuk. Actually, anything by Chuck Palahniuk.

Didn't disturb me per say, but they gave off that atmosphere.