This is an impossible request, and now you have unleashed the flood:
(not in order of preference)
Amber series by Roger Zelazny
Pern books by Anne Mccaffrey
Heinlein\'s books
Orson Scott Card\'s books
Deryni series by Katherine Kurtz
Robot/Empire/Foudation/shorts by Issac Asimov
Castle series and Starrigger trilogy by John DeChancie
Fortress Series by C. J. Cherryh
Ray Bradbury\'s books
The Riddle Master of Hed trilogy by Patricia A. McKillip
Master of the Five Magics Series by Lyndon Hardy
Memory, Sorrow & Thorn trilogy by Tad Williams
Earthsea series by Ursula K. LeGuin
Darkover series by Marion Zimmer Bradley
Belgariad/Mallorean series by David Eddings
Merlin books by Mary Stewart
Tolkein\'s books
obviously I am missing some of my favorites but I cant remember now...
[Edit] Ack! How could I forget C.S. Lewis. As well as Stephen Donaldson. Now of course I am missing some great authors and books but I have just not read them yet

[/Edit]