Books one ‘should’ have read? Classics that are generally considered part of an informal literary education?

I'm trying to work through books that are generally regarded as works you 'should' read. Not necessarily complex literary masterpieces (Dostoyevsky and the like), but classics that have become part of popular consciousness and contributed to shaping the culture a little.

To give an idea of the sort of things I mean, I've recently read: The Road, Moby Dick, Rebecca, Dr Jekyll and Mr Hyde, Brideshead Revisited, the Handmaids Tale, Wuthering Heights, 1984, Frankenstein, Post Office, Emma, the subterraneans, naked lunch, the colour purple, demon Copperhead, Grapes of Wrath, The Stranger, Midnights children. What other books of that sort of calibre would you suggest?