The Skylark of Space
by E E 'Doc' Smith (1946)

Smith had finished writing this by 1920 before its publication in Amazing Stories magazine in 1928. Widely regarded as the prototype for a host of pulp space operatic fare that would follow, the novel begins with the accidental discovery of a nuclear-type space warp process that will allow interstellar travel. Good-guy Dr Richard Seaton ends up fighting nasty Dr Marc DuQuesne for its control.

Slan
by A E van Vogt (1946)

Slans are oppressed mutant supermen, spurned by 'normal society'. The young hero survives the arrest and subsequent death of his mother - eventually learning of his extraordinary strength and psychic abilities as he reaches manhood. He falls in with Earth's dictator and plenty of political intrigue and romance follows. Super soap.

Grey Lensman
by E E 'Doc' Smith (1951)

Despite being rife with political incorrectness, the books in Smith's Lensman series are regarded as classics of the 'space opera' sub-genre. A corps of superbly-conditioned heroes armed with magical bracelets fight evil on a galaxy-spanning scale. In GL, book four in the series, a Lensman is out to destroy the enemy's Grand Base.

The City and the Stars
by Arthur C Clarke (1956)

Earthbound inhabitants of an enclosed high-tech far-future city live out utopian lifestyles, but long ago gave up travel to the stars. The adventurous hero gets out and winds up in the nature-loving city of Lys. Eventually he discovers an abandoned alien spaceship heads off to the cosmos. Rivals Childhood's End as Clarke's best novel.

Citizen Of the Galaxy
by Robert A Heinlein (1957)

Novel written for young readers that impacted on a lot of lives. A young slave boy is sold to a man who is apparently a beggar, then becomes a free trader on a starship - and eventually learns he is an heir to wealth. The book is jam-packed with so many messages about society and morality that it makes one shudder. Classic boys' stuff.

Have Space-Suit - Will Travel
by Robert A Heinlein (1958)

A volatile teenage boy wins a space-suit which helps fulfil his desire to go the moon. Some unsavoury aliens whisk him away to an ancient planet where he is forced to undergo some interpersonal development and accept his responsibilities to the human race. Bristles with energy - perhaps the best teenage sci-fi ever written.

The Sirens of Titan
by Kurt Vonnegut (1959)

Jam-packed with many of the devices later used in KV's bestselling novels - like mock religions, multi-temporal viewpoints and the manipulative Tralfamadorians. A millionaire astronaut survives flying into a chrono-synclastic infundibulum and founds the Church of God the Utterly Indifferent. Side-splitting satire of contemporary America.

The Stainless Steel Rat
by Harry Harrison (1961)

The first of a much-loved sequence, Slippery Jim diGriz is the Galaxy's smoothest con-man - until he gets caught. The obvious thing to do with a man of such immense talent is to make him a cop. He goes about conning humans, aliens and mechs - while taking on a sinister woman who is building the ultimate battleship. Inscrutable Harrison.