"Spectre of the Gun" (originally titled "The Last Gunfight") is an episode from the third season of the American science fiction television series, Star Trek, that was first broadcast on October 25, 1968, and repeated on April 4, 1969. The show was the last episode to air on NBC at 10p.m. on Fridays. It is episode #61, production #56, and was written by former producer Gene L. Coon (under the pseudonym of Lee Cronin) and directed by Vincent McEveety.

In the episode, having been found trespassing into Melkotian space, Captain Kirk and members of his crew are sent to die in a re-enactment of the Gunfight at the O.K. Corral.

The Federation starship USS Enterprise has been directed to make peaceful contact with the Melkotians on the planet Theta Kiokis II. As they near the planet, they encounter a buoy sending a warning signal to stay away, but Captain James T. Kirk orders the ship to remain on course. In orbit, Kirk joins First Officer Spock, Chief Engineer Montgomery Scott, Chief Medical Officer Dr. Leonard McCoy, and Navigator Ensign Pavel Chekov as they transport to the surface. The Melkotians, angered by their willful failure to heed the warning, instead place the landing party in a psychic illusion pulled from Kirk's memories. The landing party find themselves in an abstract landscape that appears as the wild West town of Tombstone, Arizona, though many buildings are simply facades and numerous details are missing. Further, they find their weapons have been changed from phasers to six-shooters, and they cannot contact the Enterprise.

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