Top 50 20th Century SF novels from Locus
As before, taken from thes ratings. Bold(47) if I've read them, italics(0) if I've only seen the film (or TV show). Turns out I'm bigger on SF.
1 Herbert, Frank : Dune (1965)
2 Card, Orson Scott : Ender's Game (1985)
3 Asimov, Isaac : The Foundation Trilogy (1953)
4 Simmons, Dan : Hyperion (1989)
5 Le Guin, Ursula K. : The Left Hand of Darkness (1969)
6 Adams, Douglas : The Hitchhiker's Guide to the Galaxy (1979)
7 Orwell, George : Nineteen Eighty-Four (1949)
8 Gibson, William : Neuromancer (1984)
9 Bester, Alfred : The Stars My Destination (1957)
10 Bradbury, Ray : Fahrenheit 451 (1953)
11 Heinlein, Robert A. : Stranger in a Strange Land (1961)
12 Heinlein, Robert A. : The Moon Is a Harsh Mistress (1966)
13 Haldeman, Joe : The Forever War (1974)
14 Clarke, Arthur C. : Childhood's End (1953)
15 Niven, Larry : Ringworld (1970)
16 Le Guin, Ursula K. : The Dispossessed (1974)
17 Bradbury, Ray : The Martian Chronicles (1950)
18 Stephenson, Neal : Snow Crash (1992)
19 Miller, Walter M. , Jr. : A Canticle for Leibowitz (1959)
20 Pohl, Frederik : Gateway (1977)
21 Heinlein, Robert A. : Starship Troopers (1959)
22 Dick, Philip K. : The Man in the High Castle (1962)
23 Zelazny, Roger : Lord of Light (1967)
24 Wolfe, Gene : The Book of the New Sun (1983)
25 Lem, Stanislaw : Solaris (1970)
26 Dick, Philip K. : Do Androids Dream of Electric Sheep? (1968)
27 Vinge, Vernor : A Fire Upon The Deep (1992)
28 Clarke, Arthur C. : Rendezvous with Rama (1973)
29 Huxley, Aldous : Brave New World (1932)
30 Clarke, Arthur C. : 2001: A Space Odyssey (1968)
31 Vonnegut, Kurt : Slaughterhouse-Five (1969)
32 Strugatsky, Arkady & Boris : Roadside Picnic (1972)
33 Card, Orson Scott : Speaker for the Dead (1986)
34 Brunner, John : Stand on Zanzibar (1968)
35 Robinson, Kim Stanley : Red Mars (1992)
36 Niven, Larry (& Pournelle, Jerry) : The Mote in God's Eye (1974)
37 Willis, Connie : Doomsday Book (1992)
38 Atwood, Margaret : The Handmaid's Tale (1985)
39 Sturgeon, Theodore : More Than Human (1953)
40 Simak, Clifford D. : City (1952)
41 Brin, David : Startide Rising (1983)
42 Asimov, Isaac : Foundation (1950)
43 Farmer, Philip Jose : To Your Scattered Bodies Go (1971)
44 Dick, Philip K. : Ubik (1969)
45 Vonnegut, Kurt : Cat's Cradle (1963)
46 Vinge, Vernor : A Deepness in the Sky (1999)
47 Simak, Clifford D. : Way Station (1963)
48 Wyndham, John : The Day of the Triffids (1951)
49* Keyes, Daniel : Flowers for Algernon (1966)
49* Delany, Samuel R. : Dhalgren (1975
1 Herbert, Frank : Dune (1965)
2 Card, Orson Scott : Ender's Game (1985)
3 Asimov, Isaac : The Foundation Trilogy (1953)
4 Simmons, Dan : Hyperion (1989)
5 Le Guin, Ursula K. : The Left Hand of Darkness (1969)
6 Adams, Douglas : The Hitchhiker's Guide to the Galaxy (1979)
7 Orwell, George : Nineteen Eighty-Four (1949)
8 Gibson, William : Neuromancer (1984)
9 Bester, Alfred : The Stars My Destination (1957)
10 Bradbury, Ray : Fahrenheit 451 (1953)
11 Heinlein, Robert A. : Stranger in a Strange Land (1961)
12 Heinlein, Robert A. : The Moon Is a Harsh Mistress (1966)
13 Haldeman, Joe : The Forever War (1974)
14 Clarke, Arthur C. : Childhood's End (1953)
15 Niven, Larry : Ringworld (1970)
16 Le Guin, Ursula K. : The Dispossessed (1974)
17 Bradbury, Ray : The Martian Chronicles (1950)
18 Stephenson, Neal : Snow Crash (1992)
19 Miller, Walter M. , Jr. : A Canticle for Leibowitz (1959)
20 Pohl, Frederik : Gateway (1977)
21 Heinlein, Robert A. : Starship Troopers (1959)
22 Dick, Philip K. : The Man in the High Castle (1962)
23 Zelazny, Roger : Lord of Light (1967)
24 Wolfe, Gene : The Book of the New Sun (1983)
25 Lem, Stanislaw : Solaris (1970)
26 Dick, Philip K. : Do Androids Dream of Electric Sheep? (1968)
27 Vinge, Vernor : A Fire Upon The Deep (1992)
28 Clarke, Arthur C. : Rendezvous with Rama (1973)
29 Huxley, Aldous : Brave New World (1932)
30 Clarke, Arthur C. : 2001: A Space Odyssey (1968)
31 Vonnegut, Kurt : Slaughterhouse-Five (1969)
32 Strugatsky, Arkady & Boris : Roadside Picnic (1972)
33 Card, Orson Scott : Speaker for the Dead (1986)
34 Brunner, John : Stand on Zanzibar (1968)
35 Robinson, Kim Stanley : Red Mars (1992)
36 Niven, Larry (& Pournelle, Jerry) : The Mote in God's Eye (1974)
37 Willis, Connie : Doomsday Book (1992)
38 Atwood, Margaret : The Handmaid's Tale (1985)
39 Sturgeon, Theodore : More Than Human (1953)
40 Simak, Clifford D. : City (1952)
41 Brin, David : Startide Rising (1983)
42 Asimov, Isaac : Foundation (1950)
43 Farmer, Philip Jose : To Your Scattered Bodies Go (1971)
44 Dick, Philip K. : Ubik (1969)
45 Vonnegut, Kurt : Cat's Cradle (1963)
46 Vinge, Vernor : A Deepness in the Sky (1999)
47 Simak, Clifford D. : Way Station (1963)
48 Wyndham, John : The Day of the Triffids (1951)
49* Keyes, Daniel : Flowers for Algernon (1966)
49* Delany, Samuel R. : Dhalgren (1975