Reply #52: Gonna fudge a bit here...

[HamstersFromHell]

...and include multi volume things as one item.

Ringworld (and sequels) - Larry Niven
The Mote In God's Eye (and The Gripping Hand) Larry Niven and Jerry Pournelle
Foundation Trilogy (plus prequels and sequels) Isaac Asimov
Stranger In A Strange Land - Robert A. Heinlein
Gateway (and sequels) Frederik Pohl
Riverworld Trilogy - Philip Jose Farmer
2001: A Space Odyssey (also 2010, 2061, 3001) Arthur C. Clarke
Rama Series (Clarke again)
The Engines Of God (and the rest of his "Hutch" novels) Jack McDevitt
Towing Jehovah - James Morrow

and last but not least...not a novel, but "I, Robot" for the rules that inspired a thousand other writers.