1. The Forever War - Joe Haldeman

Private William Mandella is a reluctant hero, drafted into an elite military unit to fight in a distant interstellar war against an unknowable and unconquerable alien enemy. Mandella will perform his duties and, as he survives, rise through the ranks, but his greatest test will come when he returns to Earth. Because of the effects of relativity, every time he comes home after a few months' tour of duty, centuries have gone by on Earth, making him and his fellows ever more isolated from the world for whose future they are fighting.

2. I Am Legend - Richard Matheson

Robert Neville is the last living man on earth ... but he is not alone. Every other man, woman and child on the planet has become a vampire, and they are all hungry for Neville's blood. By day he is the hunter, stalking the sleeping undead through the abandoned ruins of civilization. By night, he barricades himself in his home and prays for the dawn. How long can one man survive like this?

Probably one of the best vampire books ever written, and a truly unnerving read.

3. Cities In Flight - James Blish

James Blish's galaxy-spanning masterwork, originally published in four volumes, explores a future in which two crucial discoveries -- antigravity devices which enable whole cities to be lifted from the Earth to become giant spaceships, and longevity drugs which enable their inhabitants to live for thousands of years -- lead to the establishment of a unique Galactic empire.

4. Do Androids Dream of Electric Sheep? - Philip K. Dick

World War Terminus had left the Earth devastated. Through its ruins, bounty hunter Rick Deckard stalked, in search of the renegade replicants who were his prey. When he wasn't 'retiring' them with his laser weapon, he dreamed of owning a live animal -- the ultimate status symbol in a world all but bereft of animal life. Then Rick got his chance: the assignment to kill six Nexus-6 targets, for a huge reward. But in Deckard's world things were never that simple, and his assignment quickly turned into a nightmare kaleidoscope of subterfuge and deceit -- and the threat of death for the hunter rather than the hunted...

The inspiration for Ridley Scott's 'Blade Runner'.

5. The Stars My Destination - Alfred Bester

Such is the official verdict on Gully Foyle, unskilled space crewman. But Gully has managed to survive for 170 days in the airless purgatory of deep space after the wreck of his ship, and has escaped to Earth carrying a murderous grudge and a secret that could change the course of history. The novel which in large part inspired both the cyberpunk movement of the 1980s and the science fiction New Wave of the 1960s, 'The Stars My Destination' has an unrivalled claim to be the most influential sf book of all time.

A superb novel, and one of my favourite science-fiction novels of all time, this is a real "boys' own"-style adventure, with an unrelentingly fast pace and an incredible set of ideas.

6. Babel-17 - Samuel R. Delany

In the far future, after human civilization has spread through the galaxy, communications begin to arrive in an apparently alien language. They appear to threaten invasion, but in order to counter the threat, the messages must first be understood. BABEL-17 is the novel which catapulted Samuel R. Delany into the front rank of sf writers.

Not the greatest of the SF Masterworks series, but certainly a well-written novel, packed with great ideas.

7. Lord of Light - Roger Zelazny

Imagine a distant world where gods walk as men, but wield vast and hidden powers. Here they have made the stage on which they build a subtle pattern of alliance, love, and deadly enmity. Are they truly immortal? Who are these gods who rule the destiny of a teeming world? Their names include Brahma, Kali, Krishna and also he who was called Buddha, the Lord of Light, but who now prefers to be known simply as Sam. The gradual unfolding of the story -- how the colonization of another planet became a re-enactment of Eastern mythology -- is one of the great imaginative feats of modern science fiction.

8. The Fifth Head of Cerberus - Gene Wolfe

Far from Earth, two sister planets, Sainte Anne and Sainte Croix, circle each other. It is said that a race of shapeshifting aliens once lived here, only to become extinct when human colonists arrived. But one man believes they still exist, somewhere out in the wilderness. In The Fifth Head of Cerberus, Gene Wolfe brilliantly interweaves three tales: a scientist's son gradual discovery of the bizarre secret of his heritage; a young man's mythic dreamquest for his darker half; the mystifying chronicle of an anthropologist's seemingly-arbitrary imprisonment. Gradually, a mesmerising pattern emerges.

9. Gateway - Frederik Pohl

Wealth ... or death. Those were the choices Gateway offered. Humans had discovered this artificial spaceport, full of working interstellar ships left behind by the mysterious, vanished Heechee. Their destinations are preprogrammed. They are easy to operate, but impossible to control. Some came back with discoveries which made their intrepid pilots rich; others returned with their remains barely identifiable. It was the ultimate game of Russian roulette, but in this resource-starved future there was no shortage of desperate volunteers.

Another of my favourites in the SF Masterworks series, Pohl creates a superbly immersive world. A pity none of the other books in the Gateway series are available in the UK.

10. The Rediscovery of Man - Cordwainer Smith

The future is an interstellar empire ruled by the Lords of the Instrumentality, whose access to the drug stroon from the planet Norstrilia confers on them virtual immortality; a future in which wealthy humanity is served by the underpeople, genetically engineered animals made to look human.

Probably my least favourite of the SF Masterworks series that I have read to date, Smith creates a world which just didn't seem to work for me. The book consists of a series of short stories about the planet Nostrilia.