Difficult, I'm sure the moment I hit return to this response I'll think - Oh wait no - what about....
To Kill a Mocking Bird - Harper Lee
Of Mice and Men - Steinbeck
One Day in the life of Ivan Denisovich - Aleksandr Solzhenitsyn
Watership Down - Richard Adams
River God - Wilbur Smith
Duma Key - Stephen King
A Storm of Swords - George R. R. Martin
Curious Incident of the Dog in the Night-Time - Mark Haddon
I am Legend - Richard Matheson
The Graveyard Book - Neil Gaiman
I feel somewhat guilty about not including L.O.T.R.
, but to be truthful I never really found it that enjoyable, I actually (I know heresy) preferred the films. Please don't shoot me.