Despite being separated by thousands of light years, Star Trek: Voyager and Star Trek: Deep Space Nine crossed over inside the Mirror Universe. Voyager and Deep Space Nine were very different in tone, due to the differing approaches of the shows’ respective producers, Brannon Braga and Ira Steven Behr. Where DS9 was a serialized drama that tackled huge themes, Voyager embraced a traditional episodic approach that could sometimes feel disposable and regressive. Despite their differences in tone, DS9 and Voyager are two beloved Star Trek TV shows that still delight audiences to this day via streaming, which is a testament to the versatility and timelessness of the franchise.
As the USS Voyager was stranded in the Delta Quadrant, it was hard, but not impossible, for Star Trek: Voyager to cross over into Star Trek: Deep Space Nine‘s Alpha and Gamma Quadrant settings. In fact, there was a surprising number of Star Trek characters who guested on Voyager from Captain Hikaru Sulu (George Takei) to Commander William T. Riker (Jonathan Frakes). Creative approaches such as intervention by Q (John de Lancie), glimpses of Starfleet’s attempts to locate the missing USS Voyager, and even the Mirror Universe allowed Star Trek: Voyager to crossover with its 1990s contemporaries, including Star Trek: Deep Space Nine.
In Star Trek: Deep Space Nine season 3, episode 19, “Through the Looking Glass”, Commander Benjamin Sisko (Avery Brooks) is captured and taken to the Mirror Universe by “Smiley” O’Brien (Colm Meaney). The Rebellion in the Mirror Universe wanted Prime Sisko to convince the ex-wife of his Terran counterpart to join the resistance against the Klingon-Cardassian Alliance. As Sisko is taken to the Terran Rebellion’s enclave, he meets the Mirror Universe variants of his DS9 crew mates. In the same scene Sisko also meets the Mirror Universe version of Star Trek: Voyager‘s Lt. Tuvok (Tim Russ), leading a more logic-driven faction of the Rebellion.
Tuvok was included in “Through the Looking Glass” at the request of Rick Berman, who presumably wanted to strengthen the links between Star Trek: Deep Space Nine and Star Trek: Voyager. DS9 season 3 and Voyager season 1 aired concurrently with each other, and “Through the Looking Glass” aired on April 17, 1995, a week when there was no new episode of Voyager. In this gap between “State of Flux” and “Heroes and Demons”, therefore, a brief crossover between Voyager and DS9 was a good way to keep the fledgling Star Trek show in the minds of the audience.
“Through the Looking Glass” isn’t the only crossover between Star Trek: Voyager and Star Trek: Deep Space Nine. The Voyager pilot “Caretaker” features the USS Voyager depart from Deep Space Nine to search for the missing Tuvok and the Maquis ship, the Valjean in the Badlands. As with McCoy and Picard in the previous Star Trek pilots, DS9‘s Quark (Armin Shimerman) appeared in “Caretaker” to pass the baton to Voyager. In a scene that demonstrated how green the young Ensign Harry Kim (Garrett Wang) was, he almost falls for one of Quark’s latest scams, until he’s rescued by Lt. Tom Paris (Robert Duncan McNeill).
A version of Star Trek: Voyager‘s Doctor (Robert Picardo) appeared in Star Trek: Deep Space Nine season 5, episode 16, “Doctor Bashir, I Presume” alongside his creator Dr. Lewis Zimmerman (also Picardo). Technically, Star Trek: Deep Space Nine marks the first real appearance by the EMH’s creator, who had previously appeared in Voyager as a holographic replica. The real Zimmerman would later appear in Star Trek: Voyager season 6, episode 24, “Life Line”, which also featured Lt. Reginald Barclay (Dwight Schultz) and Counselor Deanna Troi (Marina Sirtis) further strengthening the bonds between different corners of the Star Trek universe.
All episodes of Star Trek: Deep Space Nine and Star Trek: Voyager are available to stream on Paramount+.