What Happened on the Last Episode of the Original ‘Star Trek’ & Why Was It Canceled?

STAR TREK, 1966-69, William Shatner, Sandra Smith, in the last Episode#79: — Paramount/Everett Collection

What To Know

The original Star Trek series ended with the episode “Turnabout Intruder,” featuring a controversial body-swap plot and no true series finale for fans.
Despite a passionate fan base and a successful letter-writing campaign that saved it for a third season, the show was ultimately canceled.

Before Star Trek became one of the most famous science fiction franchises ever made, it was just a struggling NBC show trying to stay on the air. The original series premiered on September 8, 1966, and followed Captain James T. Kirk (William Shatner), Spock (Leonard Nimoy), Dr. McCoy (DeForest Kelley), and the crew of the USS Enterprise as they traveled through space in the 23rd century.

It ran for three seasons and aired 79 episodes, but during its original run, the ratings were never strong enough to make NBC fully confident in it. The last episode, “Turnabout Intruder,” which aired on June 3, 1969, wasn’t written like a big series finale, so fans didn’t get a true farewell to the show or its characters. Star Trek closed with a strange body-swap episode that is now often remembered as one of the show’s most awkward and awful endings.

In the episode, the Enterprise responds to a distress call from Camus II, where an archaeological expedition has gone wrong. Kirk finds Dr. Janice Lester, a woman from his past, whom Dr. Arthur Coleman (Harry Landers) is treating. Lester is angry and bitter over the career she believes she was denied. The episode is often criticized today for how it handles her resentment. Lester uses alien technology to switch bodies with Kirk, leaving him trapped in her body while she takes over his.

STAR TREK, Leonard Nimoy, William Shatner, James Doohan, with phasers, 1966-1969.

Paramount/Everett Collection

Once she has Kirk’s appearance and authority, she tries to command the Enterprise, but the crew quickly notices that something is wrong. Spock becomes suspicious, McCoy questions the captain’s behavior, and Scotty (James Doohan) eventually realizes that the person giving orders is not really Kirk. Things get worse when Lester, still in Kirk’s body, accuses Spock, McCoy, and Scotty of mutiny. She even tries to sentence them to death, but Sulu (George Takei) and Chekov (Walter Koenig) refuse to follow the order. Eventually, the transfer reverses, Kirk returns to his own body, and Lester breaks down. The episode ends with Kirk back in command, and the Enterprise continues.

STAR TREK, from left: William Shatner, DeForest Kelley, Leonard Nimoy, 1966-69.

Everett Collection

As for why Star Trek was canceled, the main reason was ratings. The show had a loyal audience, but its Nielsen ratings were low during its original NBC run. It had already survived once because of fans. During the second season, when cancellation rumors spread, viewers launched a major letter-writing campaign to save it. NBC received a huge amount of mail and made the unusual decision to announce on-air in March 1968 that Star Trek would return for a third season.

However, NBC moved Star Trek to Friday nights at 10 pm, a bad slot for many younger viewers. Fewer NBC affiliates also carried the series than before, and the budget was cut from earlier seasons. Gene Roddenberry, frustrated with the changes, pulled back from day-to-day production, while Fred Freiberger became producer for the final season, and ultimately, NBC canceled Star Trek in 1969. Star Trek had 79 episodes, which made it well-suited to syndication, allowing local stations to air reruns regularly. In the 1970s, the series found a bigger audience than it had on NBC. Fans watched reruns, organized conventions, and helped turn the canceled show into a cult classic.