Who wrote the episode 'The City on the Edge of Forever'?

Harlan Ellison wrote the episode “The City on the Edge of Forever.” The acclaimed Star Trek story first aired on April 6, 1967, as the twenty-eighth and penultimate episode of the first season.

Ellison’s story sends Kirk and Spock into Earth’s past through the Guardian of Forever, a time portal on a ruined alien world. Dr. McCoy accidentally changes history, and Kirk falls in love with Edith Keeler, a social worker whose survival would allow a catastrophic future to unfold. Kirk must therefore allow her death, restoring the original timeline.

The episode’s production became contentious. Steven W. Carabatsos and D. C. Fontana worked on revisions, while Gene L. Coon and Gene Roddenberry were also associated with changes to the televised script. Even so, Ellison remained the credited writer and the episode’s originating author.

A frequent misconception is that the later contributors replace Ellison as the answer. They helped revise or edit the teleplay, but a quiz asking who wrote the episode conventionally expects Harlan Ellison.