Though Star Trek celebrates its 50th anniversary on Thursday—the first episode to air on TV ran on Sept. 8, 1966—the show's actual first episode is a bit older than that. The original pilot episode of Star Trek, titled "The Cage," was completed in early 1965. As these stills from the episode show, it exhibits both striking similarities with and a number of differences from the series that ended up on television.
Most noticeably, the Captain of the USS Enterprise was Christopher Pike, portrayed by Jeffrey Hunter, instead of James Kirk. Hunter backed out of the show to pursue acting in films and passed away in 1969. And, though Mr. Spock was still portrayed by Leonard Nimoy in the pilot, he was not the First Officer—that title went to a character known as Number One, portrayed by Majel Barrett. Concerning props, weapons in the pilot were referred to as "lasers," and not "phasers."
Written by Gene Roddenberry and directed by Robert Butler, the pilot was dismissed by NBC, where executives called it "too cerebral." After being persuaded by Lucille Ball, whose Desilu Studios produced the pilot, the network ordered a second pilot episode. The original, which cost NBC over $600,000 to produce, was scrapped, except for some footage that was incorporated into a later episode. Shooting started for the second pilot, "Where No Man Has Gone Before," in July 1965. This episode was the first to feature William Shatner as Captain James Kirk. It eventually aired on Sept. 22, 1966 as part of the show's first season. (A different episode, "The Man Trap," was selected as the premiere.)
"The Cage" was finally released on VHS in 1986 and aired on television in color in November 1988, with an introduction by Gene Roddenberry, as part of a two-hour Star Trek retrospective special hosted by Patrick Stewart.