The Star Trek movie or TV show.
Most of the main actors who have been involved with the franchise have defined their careers with their role, and generally, credit their time on Star Trek as one of the most important experiences of their careers. Likewise, many of the regular directors for episodes or movies have achieved great success because of their involvement. For several actors though, Star Trek has been one of the first opportunities they've had to also step behind the camera.
A surprising number of Star Trek actors have directed at least one episode or movie. For some, a handful of episodes as an experiment was all they were involved in, but others can credit Star Trek as how they got their start in a more prolific filmmaking career. To date, there have been fifteen series regulars who also directed for the franchise, and with more Star Trek content releasing all the time, that number will likely go up in the future.
Leonard Nimoy
Leonard Nimoy's role as Spock on Star Trek: The Original Series defined his career and also allowed him to explore directing. Before his work on Star Trek, Nimoy had helmed a few episodes of other shows, but his feature film debut came with Star Trek III: The Search for Spock in 1984. After this, Nimoy also directed Three Men and a Baby which was the biggest American box office hit of 1987.
William Shatner
William Shatner is best ed as Captain James T. Kirk, but he also contributed his directing talents to another memorable Star Trek project. After Leonard Nimoy's success in directing The Voyage Home, Shatner requested and was given the task of helming Star Trek V: The Final Frontier, a film which unfortunately ended up becoming a critical and commercial failure. After The Final Frontier, Shatner never directed another Star Trek project but did go on to direct episodes of TekWar, based on his novel series.
Patrick Stewart
Patrick Stewart played Captain Jean-Luc Picard on Star Trek: The Next Generation, and had continued to reprise the role in multiple other entries in the franchise. During his time on TNG, Stewart directed five episodes across multiple seasons, including such memorable episodes as "In Theory", "A Fistful of Datas", and "Phantasms". Outside of TNG, Stewart's directing credits are minimal, putting him firmly in the category of actors who only experimented with directing during their time on Star Trek.
Jonathan Frakes
Unlike Stewart, The Orville.
LeVar Burton
Star Trek: Enterprise. Burton has dabbled in directing for other shows, most recently with NCIS: New Orleans.
Michael Dorn
Although Michael Dorn first appeared playing his iconic character of Worf in TNG, it was not until he reprised the role on Deep Space Nine that he was given the opportunity to direct episodes. Dorn directed three episodes of Deep Space Nine and afterward went on to direct one for Enterprise too. Outside of Star Trek, Dorn's directing credits are minimal, so perhaps the process didn't suit him as well as some of his fellow TNG co-stars.
Gates McFadden
Gates McFadden played Doctor Beverly Crusher on TNG, and her singular directing credit is also one of the show's more memorable. McFadden directed the season 7 episode "Genesis", which tells the story of the crew beginning to de-evolve into prehistoric creatures after an experimental treatment by Doctor Crusher goes wrong. Captain Picard and Data are the only ones unaffected and must work to save the ship and find a way to reverse the evolutionary processes. While a classic TNG episode, "Genesis" is McFadden's only directing credit for both the franchise and her career in general.
Avery Brooks
Avery Brooks made history on Star Trek: Deep Space Nine as Benjamin Sisko, the franchise's first black Captain. Along with this, Brooks stepped behind the camera for nine episodes of the show. His directing credits include such memorable episodes as "Reed", which featured Star Trek's first-ever LGBTQ+ romance, and "Far Beyond the Stars", which has been credited as one of the greatest Star Trek episodes of all time. Brooks did not take the opportunity to direct outside the franchise after the series was over, but his contributions will not soon be forgotten.
Rene Auberjonois
Rene Auberjonois played Odo on Deep Space Nine, a character who is considered a favorite among Star Trek viewers. In addition to playing Odo, Auberjonois directed nine episodes of Deep Space Nine, beginning in season 3 and continuing through the rest of the series. Auberjonois is one of the few actors who had previous directing experience before his role on Deep Space Nine too. It seems Auberjonois ultimately viewed acting as a better fit, as he did not go on to helm anything else after Deep Space Nine.
Alexander Siddig
Alexander Siddig ed the ranks of his fellow Deep Space Nine actors who also directed in seasons 5 and 6 with the episodes "Business as Usual" and "Profit and Lace". Both mainly featured Armin Shimmerman's Quark as the main character, and while "Business as Usual" was reviewed favorably, "Profit and Lace" did not fare so well with critics. Like so many of his fellow actors, Siddig's directing career began and ended with Star Trek.
