Summary
Although it wasn’t the franchise’s first character swap,Star Trek: Voyager’s Kes (Jennifer Lien) and Seven of Nine (Jeri Ryan) switch was more unique than character changes in otherStar Trekprojects.Voyager’s cast of charactersstayed mostly the same throughout the show’s run, except for the departure of Kes and the introduction of Seven at the start of season 4.The swap happened over season 4’s first two episodes, “Scorpion, Part II” and “The Gift,“and was accomplished well, all things considered.
During “The Gift,” Kes’s latent mental abilities began to evolve rapidly thanks to Species 8472, to the point where she was a danger to the USS Voyager and her crew. As a result, Kes voluntarily left the ship and ascended to a higher plane of existence. She left behind Seven, who had just been rescued from the Borg Collective, and was convinced by Captain Janeway (Kate Mulgrew) to embrace her transition back to humanity at the end of the episode. While it may seem surprising,this type of on-screen, narratively accomplished transition was rare forStar TrekTV shows.

The Complete Star Trek Timeline Explained
Star Trek’s timeline spans a thousand years of Starfleet and the United Federation of Planets, with alternate realities and time travel galore.
Star Trek: Voyager’s Kes/Seven Of Nine Swap Was Different From TNG And DS9
Voyager accomplished its character swap in a unique way
Previous character swaps in otherStar Trekprojects had eitherhappened off-screen or not been about switching one unique character for another. The two biggest character changes that happened in the franchise beforeVoyagerwere Dr. Pulaski (Diana Muldaur) taking over for Dr. Crusher (Gates McFadden) in season 2 ofStar Trek: The Next Generationand Ezri Dax (Nicole de Boer) replacingJadzia Dax (Terry Farrell) onStar Trek: Deep Space Nine. Both of these swaps had some similarities toVoyager’s Kes/Seven swap, butVoyagerwas distinct from both in a few important ways.
The on-screen, plot-supported switch of two characters hadn’t happened in aStar Trekseries beforeVoyager, and continued to be rare in the 1990s era of the franchise.

Dr. Pulaski’s transition to and from the cast ofStar Trek: TNGhappened entirely off-screen both times. She was introduced without much fanfare in the first episode of season 2 and was gone by the first episode of season 3 in the same fashion. Likewise, although Ezri Dax was a different character from Jadzia Dax, she was also more of an extension of Jadzia than a completely unique character.The on-screen, plot-supported switch of two characters hadn’t happened in aStar Trekseries beforeVoyager, and continued to be rare in the 1990s era of the franchise.
Why Modern Star Trek Takes A Different Approach To Main Cast Rotation
Modern Star Trek series do things differently
Unlike the classicStar Trekshows, however, newer series take a much different approach to swapping characters in and out of their main casts.BothStar Trek: DiscoveryandStar Trek: Picardwent through several drastic main cast changesduring their respective five and three seasons. While some key members ofDiscovery’s core cast of charactersremained the same, many other members came and went, especially after the show’s time jump to the 32nd century. Similarly,Picardcompletely overhauled its main cast in season 3 to bring in the former stars ofStar Trek: TNG.
This seems to bethe result of focusing on a serialized narrative rather than episodic storytelling. If certain NewTrekcharacters were or were not important to the central plot of a season, they would be swapped in or out to accommodate. This is less the case withStar Trek: Strange New Worlds, but even that show’s more episodic narrative has seen some cast changes, like the death of Hemmer (Bruce Horak) in season 1. ModernStar Trekmade a lot of changes to the franchise, and regular cast swapping similar toStar Trek: Voyageris one of them.

Star Trek: Voyager
Cast
The fifth entry in the Star Trek franchise, Star Trek: Voyager, is a sci-fi series that sees the crew of the USS Voyager on a long journey back to their home after finding themselves stranded at the far ends of the Milky Way Galaxy. Led by Captain Kathryn Janeway, the series follows the crew as they embark through truly uncharted areas of space, with new species, friends, foes, and mysteries to solve as they wrestle with the politics of a crew in a situation they’ve never faced before.