"The Cage" is the first pilot episode of the American television series Star Trek. It was completed on January 22, 1965 (with a copyright date of 1964). The episode was written by Gene Roddenberry and directed by Robert Butler. It was rejected by NBC in February 1965, and the network ordered another pilot episode, which became "Where No Man Has Gone Before". Much of the original footage from "The Cage" was later incorporated into the season 1 two-part episode "The Menagerie" (1966); however, "The Cage" was first released to the public on VHS in 1986, with a special introduction by Gene Roddenberry, as a hybrid of the color footage that was used in "The Menagerie" and black and white footage which was not used in "The Menagerie". It was not broadcast on television in its complete all-color form until 1988. The black and white version and all-color version were also released in various standard-definition media including LaserDisc, VHS, and DVD formats.

The story concerns a starship crew's investigation of a far-off planet which was the site of a shipwreck eighteen years earlier and their encounter with telepathic aliens who seek a human male specimen for their menagerie. The pilot introduced Mr. Spock, played by Leonard Nimoy, who was the only cast member to be retained for the series in his original role.