The 52nd episode of Gene Roddenberry’s science fiction series Star Trek premieres on NBC. A tale of patriotism perverted into a belief system, The Omega Glory is one of three Roddenberry scripts originally pitched to NBC as potential pilot episodes before the start of filming on season one. 
The 53rd episode of Gene Roddenberry’s science fiction series Star Trek premieres on NBC. In true sixties style, the story’s “ultimate computer” is depicted as a giant mainframe with psychedelic lights; William Marshall guest stars.
The 54th episode of Gene Roddenberry’s science fiction series Star Trek premieres on NBC. Long before contest-style “reality TV” exists, Roddenberry predicts it with unsettling accuracy, even if he’s a little bit off on the details. Ian Wolfe guest stars.
The 55th episode of Gene Roddenberry’s science fiction series Star Trek premieres on NBC, guest starring Robert Lansing and Teri Garr. An oddball episode concerning itself heavily with its time-traveling guest star, Assignment: Earth is actually a sneaky “pilot” for a potential Star Trek spinoff – and Gene Roddenberry’s hedge against unemployment, as he has every reason to believe, at the end of Star Trek’s second season, that his series is about to be cancelled. 
The 56th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This is the first episode of the third season, and the first overseen by new producer Fred Freiberger. Marj Dusay guest stars.
The 57th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Joanna Linville guest stars as the Romulan Commander.
The 58th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Sabrina Scharf guest stars as Miramanee; William Shatner is Kirok.
The 59th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Melvin Belli guest stars; future Space Academy cast members Pamelyn Ferdin and Brian Tochi both appear as children in this episode.
The 60th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Diana Muldaur guest stars, her second guest shot on the series; she will later appear as a regular in the second season of Star Trek: The Next Generation.
The 61st episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Ron Soble and Rex Holman guest star.
The 62nd episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Michael Ansara guest stars as Kang.
The 63rd episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Kate Woodville and Byron Morrow guest star.
The 64th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This marks the first appearance of the Tholians and, though they will be mentioned frequently in later Star Trek spinoffs, the last appearance until the 21st century spinoff series Star Trek: Enterprise.
The 65th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This episode features one of the earliest interracial kisses in the history of American scripted television; a handful of NBC affiliates in the southern United States pre-empt the episode as a result.
The 66th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Kathie Browne and Jason Evers (Wrangler, Robot Monster) guest star.
The 67th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Kathryn Hays guest stars in a role without any dialogue at all.
The 68th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. France Nuyen guest stars.
The 69th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Steve Inhat and Yvonne Craig (Batman) guest star.
The 70th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Frank Gorshin (Batman) guest stars.
The 71st episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Sharon Acker and Gene Dynarski guest star.
The 72nd episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Lee Meriwether (Batman) guest stars.
The 73rd episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This episode is co-written by Shari Lewis, better known as the puppeteer behind Lambchop.
The 74th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This episode sees Spock use a version of a Vulcan mind-meld on Kirk, urging him to “forget”; the later movies will reveal that this memory manipulation technique has an opposite number: “remember”…
NBC announces that it is dropping Star Trek from the fall 1969 network schedule. Having taken the show’s Friday night “death slot” as a sign of things to come, Gene Roddenberry has already begun seeking greener pastures, leaving the day-to-day showrunner duties to Fred Freiberger. Roddenberry also has no plans to manipulate fan protests against the cancellation this time (as he had done in 1967 and 1968); some NBC publicity and promotions executives are surprised when the seemingly inevitable backlash fails to materialize.
The 75th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This infamously “hippie themed” episode guest stars Charles Napier.
The 76th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Jeff Corey guest stars.
The 77th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Lee Bergere and Barry Atwater guest star. This episode features the last Klingon seen in the original television series.
The 78th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. Ian Wolfe and Mariette Hartley guest star. The last episode of Star Trek, originally scheduled for the following week, is pre-empted and aired months later with little fanfare.
Having completed its purchase of Desilu Studios, Paramount runs the first print advertisement in Vol. 76, Issue 12 of Broadcasting Magazine, offering Star Trek reruns in syndication. Even though the last episode has yet to air on NBC, it is perhaps telling that the ad promises a set number of “79 episodes of constant quality, now being seen in over 65 countries around the world” – confirmation that there will be no further episodes beyond the current season.
The 79th episode of Gene Roddenberry’s science fiction series Star Trek airs on NBC. This was the final episode produced or broadcast; Gene Roddenberry, having caught the meaning of the series’ move to a Friday night “death slot,” had already moved on to greener pastures without making arrangements for another fan protest for Star Trek’s renewal.