1. Robert Heinlein
2. Issac Asimov
3. Lois McMaster Bujold
4. Mercedes Lackey
5. Steve Perry
6. Stephen Donaldson
7. Susan Cooper
8. Raymond Bradbury
9. Rod Serling
10. Frank Herbert
11. Roger Zelany
12. Alfred Bester
13. George R. Stewart
14. Dean Koontz
15. Michael Moorcock
*Note: I don't consider Stephen King a SF/F author but he is an author I will never forget.