X Minus One is an American half-hour science fiction radio drama series that was broadcast from April 24, 1955, to January 9, 1958, in various timeslots on NBC.

[1][2] Initially a revival of NBC's Dimension X (1950–51), the first 15 episodes of X Minus One were new versions of Dimension X episodes, but the remainder were adaptations by NBC staff writers, including Ernest Kinoy and George Lefferts,[1] of newly published science fiction stories by leading writers in the field, including Isaac Asimov, Ray Bradbury, Philip K. Dick, Robert A. Heinlein, Frederik Pohl and Theodore Sturgeon, along with some original scripts by Kinoy and Lefferts.

Included in the series were adaptations of Robert Sheckley's "Skulking Permit", Bradbury's "Mars Is Heaven", Heinlein's "Universe" and "The Green Hills of Earth", Pohl's "The Tunnel under the World", J. T. McIntosh’s "Hallucination Orbit", Fritz Leiber’s "A Pail of Air", and George Lefferts' "The Parade".

The National Broadcasting Company, in cooperation with Street & Smith, publishers of Astounding Science Fiction presents... X Minus One.

However, the early 1970s brought a wave of nostalgia for old-time radio; a new experimental episode, "The Iron Chancellor" by Robert Silverberg, was produced in 1973, but it failed to revive the series.