One of Britain's more influential science-fiction magazines, Science-Fantasy was launched by Nova Publications in 1950 as a companion publication to New Worlds. Originally edited by Walter Gillings, it came under the control of New Worlds editor John Carnell with issue 3. In 1964, it was sold to Roberts & Vinter, after which its fortunes declined.

Carnell focused strongly on the literary quality of the stories published in Science-Fantasy. The magazine focused equally on science fiction (publishing, for example, early stories by Brian Aldiss) and fantasy (including Michael Moorcock's early Elric of Melniboné stories). During the early 1960s, often considered the highpoint of the magazine's run, the three mainstay writers were Michael Moorcock, Thomas Burnett Swann, and J.G. Ballard.