Just got a top 100 list of SciFi books from a friend.... guess I have some more reading to do.
If you are interested lookup Nebula and Hugo awards for more great Science Fiction novels.
Note: Science Fiction is fiction based on science. NOT FANTASY!
Bold are items I have read previously.
1 - Ender's Game - Orson Scott Card - 1985
2 - Dune - Frank Herbert - 1965
3- Foundation - Isaac Asimov - 1951
4 - Hitchhiker's Guide to the Galaxy - Douglas Adams - 1979
5 - 1984 - George Orwell - 1949
6 - Stranger in a Strange Land - Robert A Heinlein - 1961
7 - Fahrenheit 451 - Ray Bradbury - 1954
8 - 2001: A Space Odyssey - Arthur C Clarke - 1968
9 - Starship Troopers - Robert A Heinlein - 1959
10 - I, Robot - Isaac Asimov - 1950
11 - Neuromancer - William Gibson - 1984
12 - Do Androids Dream of Electric Sheep - Philip K *** - 1968
13 - Ringworld - Larry Niven - 1970
14 - Rendezvous With Rama - Arthur C Clarke - 1973
15 - Hyperion - Dan Simmons - 1989
16 - Brave New World - Aldous Huxley - 1932
17 - The Time Machine - H G Wells - 1895
18 - Childhood's End - Arthur C Clarke - 1954
19 - The Moon is a Harsh Mistress - Robert A Heinlein - 1966
20 - The War of the Worlds - H G Wells - 1898
21 - The Forever War - Joe Haldeman - 1974
22 - The Martian Chronicles - Ray Bradbury - 1950
23 - Slaughterhouse Five - Kurt Vonnegut - 1969
24 - Snow Crash - Neal Stephenson - 1992
25 - The Mote in God's Eye - Niven & Pournelle - 1975
26 - The Left Hand of Darkness - Ursula K Le Guin - 1969
27 - Speaker for the Dead - Orson Scott Card - 1986
28 - Jurassic Park - Michael Crichton - 1990
29 - The Man in the High Castle - Philip K *** - 1962
30 - The Caves of Steel - Isaac Asimov - 1954
31 - The Stars My Destination - Alfred Bester - 1956
32 - Gateway - Frederik Pohl - 1977
33 - Lord of Light - Roger Zelazny - 1967
34 - Solaris - Lem Stanislaw - 1961
35 - 20,000 Leagues Under the Sea - Jules Verne - 1870
36 - A Wrinkle in Time - Madelein L'Engle - 1962
37 - Cat's Cradle - Kurt Vonnegut - 1963
38 - Contact - Carl Sagan - 1985
39 - The Andromeda Strain - Michael Crichton - 1969
40 - The Gods Themselves - Isaac Asimov - 1972
41 - A Fire Upon the Deep - Vernor Vinge - 1991
42 - Cryptonomicon - Neal Stephenson - 1999
43 - The Day of the Triffids - John Wyndham - 1951
44 - UBIK - Philip K *** - 1969
45 - Time Enough For Love - Robert A Heinlein - 1973
46 - A Clockwork Orange - Anthony Burgess - 1962
47 - Red Mars - Kim Stanley Robinson - 1992
48 - Flowers for Algernon - Daniel Keyes
49 - A Canticle for Leibowitz - Walter M Miller - 1959
50 - The End of Eternity - Isaac Asimov - 1955
51 - Battlefield Earth - L Ron Hubbard - 1982
52 - Frankenstein - Mary Shelley - 1818
53 - Journey to the Center of the Earth - Jules Verne - 1864
54 - The Dispossessed - Ursula K Le Guin - 1974
55 - The Diamond Age - Neal Stephenson - 1995
56 - The Player of Games - Iain M Banks - 1988
57 - The Reality Dysfunction - Peter F Hamilton - 1996
58 - Startide Rising - David Brin - 1983
59 - The Sirens of Titan - Kurt Vonnegut - 1959
60 - Eon - Greg Bear - 1985
61 - Ender's Shadow - Orson Scott Card - 1999
62 - To Your Scattered Bodies Go - Philip Jose Farmer - 1971
63 - A Scanner Darkly - Philip K *** - 1977
64 - Lucifer's Hammer - Niven & Pournell - 1977
65 - The Handmaid's Tale - Margaret Atwood - 1985
66 - The City and the Stars - Arthur C Clark - 1956
67 - The Stainless Steel Rat - Harry Harrison - 1961
68 - The Demolished Man - Alfred Bester - 1953
69 - The Shadow of the Torturer - Gene Wolfe - 1980
70 - Sphere - Michael Crichton - 1987
71 - The Door Into Summer - Robert A Heinlein - 1957
72 - The Three Stigmata of Palmer Eldritch - Philip K *** - 1964
73 - Revelation Space - Alastair Reynolds - 2000
74 - Citizen of the Galaxy - Robert A Heinlein - 1957
75 - Doomsday Book - Connie Willis - 1992
76 - Ilium - Dan Simmons - 2003
77 - The Invisible Man - H G Wells - 1897
78 - Have Space-Suit Will Travel - Robert A Heinlein - 1958
79 - The Puppet Masters - Robert A Heinlein - 1951
80 - Out of the Silent Planet - C S Lewis - 1938
81 - A Princess of Mars - Edgar Rice Burroughs - 1912
82 - The Lathe of Heaven - Ursula K Le Guin - 1971
83 - Use of Weapons - Iain M Banks - 1990
84 - The Chrysalids - John Wyndham - 1955
85 - Way Station - Clifford Simak - 1963
86 - Flatland - Edwin A Abbott - 1884
87 - Altered Carbon - Richard Morgan - 2002
88 - Old Man's War - John Scalzi - 2005
90 - The Road - Cormac McCarthy - 2006
91 - The Postman - David Brin - 1985
93 - VALIS - Philip K *** - 1981
96 - The Lost World - Arthur Conan Doyle - 1912
97 - The Many-Colored Land - Julian May - 1981
98 - Gray Lensman - E E 'Doc' Smith - 1940
99 - The Uplift War - David Brin - 1987