Let me start you off with two I should not have read as a fairly young child.
My Dad used to leave his books in downstairs loo so I read Cujo - which gave me horrendous nightmares for months and a Roman era sex and slaves romp (no idea what it was called - a toga ripper!) which was very graphic and rather inappropriate to be left in the reach of children! There were also countless cold war era spy novels but they were quite exciting and educational (rubbish covers though guns and blood stains and shapely legs + high heels!).
So no Stephen King till they are over at least 12. No literary porn. And I will add no Jordan Bios!
what else?