I'll throw a few classics up that haven't been mentioned (and two of the best sci-fi works which I'm also counting as literary classics because they're as brilliant as anything else):
Revolutionary Road by Richard Yates
Been Down So Long It Looks Like Up to Me by Richard Farina
The Adventures of Augie March by Saul Bellow
Independent People by Halldor Laxness
Stars in My Pocket Like Grains of Sand by Samuel R. Delany
Dhalgren by Samuel R. Delany