Which episode was the final first-run broadcast of Star Trek: The Original Series?

The final first-run broadcast of Star Trek: The Original Series was “Turnabout Intruder.”

It is the twenty-fourth and final episode of the show’s third season. The story follows Dr. Janice Lester, who exchanges bodies with Captain Kirk and attempts to seize command of the Enterprise. The episode was written by Arthur H. Singer from a story by Gene Roddenberry and directed by Herb Wallerstein.

“Turnabout Intruder” was originally scheduled for March 28, 1969, but NBC pre-empted it for coverage of former president Dwight D. Eisenhower’s death. It eventually aired after the series returned from a two-month break in a new Tuesday time slot.

The other options are earlier third-season episodes: “The Cloud Minders,” “The Savage Curtain,” and “All Our Yesterdays.” A useful distinction is that “Turnabout Intruder” was the final episode broadcast during the original NBC run, even though Star Trek later continued in animated and feature-film forms.