Titles marked in bold I either own or have read (or both!)
GOLLANCZ SCIENCE FICTION MASTERWORKS SERIES
- The Forever War by Joe Haldeman
- I Am Legend by Richard Matheson
- Cities in Flight by James Blish
- Do Androids Dream of Electric Sheep? by Philip K. Dick
- The Stars My Destination by Alfred Bester
- Babel-17 by Samuel R. Delany
- Lord of Light by Roger Zelazny
- The Fifth Head of Cerberus by Gene Wolfe
- Gateway by Frederik Pohl
- The Rediscovery of Man by Cordwainer Smith
- Last and First Men by Olaf Stapledon
- Earth Abides by George R. Stewart
- Martian Time-Slip by Philip K. Dick
- The Demolished Man by Alfred Bester
- Stand on Zanzibar by John Brunner
- The Dispossessed by Ursula K. Le Guin
- The Drowned World by J. G. Ballard
- The Sirens of Titan by Kurt Vonnegut
- Emphyrio by Jack Vance
- A Scanner Darkly by Philip K. Dick
- Star Maker by Olaf Stapledon
- Behold the Man by Michael Moorcock
- The Book of Skulls by Robert Silverberg
- The Time Machine and The War of the Worlds by H. G. Wells
- Flowers for Algernon Daniel Keyes
- Ubik by Philip K. Dick
- Timescape by Gregory Benford
- More Than Human by Theodore Sturgeon
- Man Plus by Frederik Pohl
- A Case of Conscience by James Blish
- The Centauri Device by M. JohnHarrison
- Dr. Bloodmoney by Philip K. Dick
- Non-Stop by Brian Aldiss
- The Fountains of Paradise by Arthur C. Clarke
- Pavane by Keith Roberts
- Now Wait for Last Year by Philip K. Dick
- Nova by Samuel R. Delany
- The First Men in the Moon by H. G. Wells
- The City and the Stars by Arthur C. Clarke
- Blood Music by Greg Bear
- Jem by Frederik Pohl
- Bring the Jubilee by Ward Moore
- VALIS by Philip K. Dick
- The Lathe of Heaven by Ursula K. Le Guin
- The Complete Roderick by John Sladek
- Flow My Tears, the Policeman Said by Philip K. Dick
- The Invisible Man by H. G. Wells
- Grass by Sheri S. Tepper
- A Fall of Moondust by Arthur C. Clarke
- Eon by Greg Bear
- The Shrinking Man by Richard Matheson
- The Three Stigmata of Palmer Eldritch by Philip K. Dick
- The Dancers at the End of Time by Michael Moorcock
- The Space Merchants by Frederik Pohl and Cyril M. Kornbluth
- Time Out of Joint by Philip K. Dick
- Downward to the Earth by Robert Silverberg
- The Simulacra by Philip K.Dick
- The Penultimate Truth by by Philip K. Dick
- Dying Inside by Robert Silverberg
- Ringworld by Larry Niven
- The Child Garden by Geoff Ryman
- Mission of Gravity by Hal Clement
- A Maze of Death by Philip K. Dick
- Tau Zero by Poul Anderson
- Rendezvous with Rama by Arthur C.Clarke
- Life During Wartime by Lucius Shepard
- Where Late the Sweet Birds Sang by Kate Wilhelm
- Roadside Picnic by Arkady and Boris Strugatsky
- Dark Benediction by Walter M. Miller, Jr.
- Mockingbird by Walter Tevis
- Dune by Frank Herbert
- The Moon Is a Harsh Mistress by Robert A. Heinlein
- The Man in the High Castle by Philip K. Dick
- The Conan Chronicles: Volume 1: The People of the Black Circle by Robert E. Howard
- The Book of the New Sun. Volume 1 by Gene Wolfe
- Little, Big by John Crowley
- King of Elfland's Daughter by Lord Dunsany
- Tales of the Dying Earth by Jack Vance
- Time and the Gods by Lord Dunsany
- The Broken Sword by Poul Anderson
- Elric by Michael Moorcock
- The Chronicles of Amber by Roger Zelazny
- Replay by Ken Grimwood
- The Book of the New Sun. Volume 2 by Gene Wolfe
- Lyonesse: Suldrun's Garden by Jack Vance
- The Anubis Gates by Tim Powers
- Lyonesse: The Green Pearl and Madouc by Jack Vance
- Fevre Dream by George R.R. Martin
- Something Wicked This Way Comes by Ray Bradbury
- The First Book of Lankhmar by Fritz Leiber
- The Land of Laughs by Jonathan Carroll
- The Worm Ouroboros by Eric Rücker Eddison
- The Forgotten Beasts of Eld by Patricia A. McKillip
- Darker Than You Think by Jack Williamson
- The Compleat Enchanter by L. Sprague de Camp
- Hour Of The Dragon by Robert E. Howard
- Voice of Our Shadow by Jonathan Carroll
- The Emperor of Dreams by Clark Ashton Smith
- The Riddle-Master's Game by Patricia A. McKillip
- A Voyage to Arcturus by David Lindsay
- The Iron Dragon's Daughter by Michael Swanwick
- Corum: The Prince in the Scarlet Robe by Michael Moorcock
- The History of the Runestaff by Michael Moorcock
- The House on the Border Land and Other Stories by William Hope Hodgson
- Three Hearts and Three Lions by Poul Anderson
- Viriconium by M. John Harrison
- Lud-In-The-Mist by Hope Mirrlees
- Beauty by Sheri S. Tepper
- Time and Again by Jack Finney
- Mistress of Mistresses by Eric Rücker
- Gloriana by Michael Moorcock
- The Well of the Unicorn by Fletcher Pratt
- Swords Against Death by Fritz Leiber
- Peace by Gene Wolfe
- The Dragon Waiting : A Masque of History by John M. Ford
- Black Gods and Scarlet Dreams by Catherine Lucille Moore
- The Drawing of the Dark by Tim Powers
- The Mabinogion by Evangeline Walton
- Grendel by John Champlin Gardner Jr.
- Was by Geoff Ryman
- Song of Kali by Dan Simmons
- Sea Kings of Mars and Otherwordly Stories by Leigh Brackett
- The Mark Of The Beast And Other Fantastical Tales by Rudyard Kipling
So what do you think? Which books would you include on a 'best of' science fiction or fantasy? Add your choices using the comments.