Erich Maria Remarque is a writer that I can pick up anything of and know I will enjoy it greatly. The only reason I haven't read everything he has written is because I don't know German and I would like to save some of them to read later in life. He is just a great writer who lived through some tough times and writes about people living through tough times and coping with it. For anyone interested in reading his stuff, I would say his classic anti-war novel, All Quiet on the Western Front is the best place to start.
I am also very fond of Ernest Hemingway, Ismail Kadare, Herman Melvill, Charles Dickens, Philip K. Dick, Douglas Adams, Kurt Vonnegut, Richard Matheson, George Orwell, Ray Bradbury, Harper Lee, H.G. Wells, Victor Hugo.
And a couple of one hit wonders (or people whom I have only read one book of but been overly impressed by), Chuck Palahnuik, Pierre Boulle, Anthony Burgess.