"The Man Trap" was the first episode of the American science fiction television series Star Trek to be broadcast. It aired on NBC on September 8, 1966, and two days earlier on Canadian network CTV. Set in the 23rd century, the series follows the adventures of Captain James T. Kirk (William Shatner) and his crew aboard the Starfleet starship USS Enterprise. In this episode, the crew visit an outpost to conduct medical exams on the residents, only to be attacked by a shapeshifting alien creature seeking to extract salt from their bodies. "The Man Trap" was written by George Clayton Johnson and directed by Marc Daniels.

The story—part of the original Star Trek pitch by series creator Gene Roddenberry—was first assigned to Lee Erwin. Johnson took on the writing duties after Roddenberry disliked his work on another plot proposal. Johnson's first draft was titled "Damsel With a Dulcimer", incorporating elements from his Twilight Zone episode "The Four of Us Are Dying". Roddenberry, producer Robert H. Justman and story editor John D. F. Black all tweaked elements of the episode, including the title. "The Man Trap" was the sixth episode to be filmed, but the first to be shot to schedule. Prop creator Wah Chang and costume designer William Ware Theiss created the creature.

The episode was chosen as the first of the series to be broadcast by the studio due to the horror-based plot. "The Man Trap" placed first in the timeslot with a Nielsen rating of 25.2 percent for the first half-hour and 24.2 for the remainder. After broadcast, reviewers criticized the levels of violence, but praised the acting. More recent appraisals have been mixed; praise has been given to the plot and diverse cast, but Hollywood.com listed it as among the worst episodes of the series. The creature has been dubbed the "salt vampire" by fans; it was redesigned for possible inclusion in the 2009 film Star Trek, but was not used.

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