"The Man Trap" is the first episode of season one of the American science fiction television series Star Trek. Written by George Clayton Johnson and directed by Marc Daniels, it featured design work by Wah Chang and first aired in the United States on September 8, 1966.

In the episode, the crew visit an outpost on planet M-113 to conduct routine medical exams on the residents, only to be attacked by a shapeshifting alien who kills by extracting salt from the victim's body.

This was the first Star Trek episode to air on television, although the sixth to be filmed; it was chosen as the first of the series to be broadcast by the studio due to the horror plot. "The Man Trap" placed first in the timeslot with a Nielsen rating of 25.2 for the first half-hour and 24.2 for the remainder. It aired two days earlier on Canadian network CTV.

Star Trek is an American science-fiction television series created by Gene Roddenberry that follows the adventures of the starship USS Enterprise (NCC-1701) and its crew. It later acquired the retronym of Star Trek: The Original Series (TOS) to distinguish the show within the media franchise that it began.

The show is set in the Milky Way galaxy, circa 2266–2269. The ship and crew are led by Captain James T. Kirk (William Shatner), First Officer and Science Officer Spock (Leonard Nimoy), and Chief Medical Officer Leonard H. "Bones" McCoy (DeForest Kelley). Shatner's voice-over introduction during each episode's opening credits stated the starship's purpose:

Space: the final frontier. These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before.

Norway Productions and Desilu Productions produced the series from September 1966 to December 1967. Paramount Television produced the show from January 1968 to June 1969. Star Trek aired on NBC from September 8, 1966, to June 3, 1969. It was first broadcast on September 6, 1966, on Canada's CTV network. Star Trek's Nielsen ratings while on NBC were low, and the network cancelled it after three seasons and 79 episodes. Several years later, the series became a hit in broadcast syndication, remaining so throughout the 1970s, achieving cult classic status and a developing influence on popular culture. Star Trek eventually spawned a franchise, consisting of eight television series, 13 feature films, and numerous books, games, and toys, and is now widely considered one of the most popular and influential television series of all time.