Here is every Star Trek: Voyager character who appeared in other Star Trek TV series and movies. Premiering in 1995, Star Trek: Voyager was the flagship series of UPN (United Paramount Network) and it was historic for being the first Star Trek series headlined by a female Captain, Kate Mulgrew, who played Captain Kathryn Janeway. In season 4, Jeri Ryan joined Star Trek: Voyager as Seven of Nine and became the series' cover girl and most popular character.
The 1990s were the apex of Star Trek's popularity, with the cast of Star Trek: The Next Generation appearing in a series of feature films while Star Trek: Deep Space Nine kept the franchise thriving on television. Star Trek: Voyager was the second spinoff from TNG and Paramount considered it to be the new flagship of the entire franchise. Its premise was also unique since the U.S.S. Voyager was lost in the unexplored Delta Quadrant and had to make the perilous, years-long journey to return home to Earth. Despite the creative difficulties, thanks to Voyager's crew being millions of lightyears away from the Federation, the Star Trek franchise still found some creative ways to involve some of Voyager's cast throughout the franchise.
After Star Trek: Voyager went off the air, the series and its characters remained dormant for many years as the Star Trek franchise focused on reboots and prequel series, but Star Trek: Picard delighted Voyager's fans by integrating Seven of Nine into Patrick Stewart's TNG sequel series on CBS All-Access. Fans hope to learn more about what became of Voyager's crew going forward now that Seven of Nine has kicked the door open for more potential crossovers in the future.
Admiral Kathryn Janeway In Star Trek: Nemesis
Fresh off the end of Star Trek: Voyager in 2001, Kate Mulgrew cameoed in 2002's Star Trek: Nemesis as Admiral Kathryn Janeway. The U.S.S. Voyager's former Captain was promoted after bringing her ship and crew home from being lost in the Delta Quadrant for seven years. Janeway gave Captain Jean-Luc Picard (Patrick Stewart) his marching orders to travel to Romulus because he's been invited to meet the new Praetor, a Reman named Shinzon (Tom Hardy), who was a clone of Picard.
Janeway also wryly joked that Picard seems to get "all the easy assignments", and she's no stranger to Starfleet Captains succeeding at a seemingly impossible task. Star Trek: Nemesis was Janeway's last canonical appearance in Star Trek and there has been no indication yet of her whereabouts in Star Trek: Picard's era.
Seven of Nine In Star Trek: Picard
Seven of Nine (Jeri Ryan) was the most popular Star Trek: Voyager character and she was the most logical choice to join Star Trek: Picard's cast due to her shared history with Jean-Luc of being assimilated by the Borg. Seven appeared at the end of the fourth episode of Star Trek: Picard season 1, "Absolute Candor", when she mounted a surprise rescue, and she appeared in a total of 5 episodes. By the end of Star Trek: Picard season 1, Seven had taken control of the Romulans' Borg Cube Artifact and she joined Picard's crew aboard La Sirena. Seven also began a romantic relationship with Raffi Musiker (Michelle Hurd).
Seven's history since the end of Star Trek: Voyager has been tragic: She left Earth because of the Federation's ban on synthetic life since her Borg implants are a permanent part of her. Seven joined the Fenris Rangers and helped patrol Romulan space but Icheb (Casey King), who she considered to be her son, was murdered for his Borg parts. Seven's return in Star Trek: Picard was incredibly well-received and she looks to be a major player in Star Trek: Picard season 2.
The Doctor In Star Trek: First Contact
Star Trek: Voyager's Doctor (Robert Picardo) was an Emergency Medical Hologram and it makes sense that the EMH would become standard technology on new Starfleet ships built after the U.S.S. Voyager, such as the Sovereign-class U.S.S. Enterprise-E. In Star Trek: First Contact, Dr. Beverly Crusher (Gates McFadden) activated the Enterprise's EMH and told him to distract the Borg trying to break into Sickbay while she and her patients escaped through the Jeffries Tube. The EMH replied, "I'm a doctor, not a doorstop."
The Enterprise's EMH isn't actually the same character as the EMH who would become the U.S.S. Voyager's full-time Doctor, but the EMH technology and its avatar were derived from its creator, Dr. Lewis Zimmerman so it's logical that all of the EMH holograms look alike. This idea would be explored further when Dr. Zimmerman appeared in Star Trek: Deep Space Nine a few months after Star Trek: First Contact aired in theaters.
The Doctor & Lewis Zimmerman In Star Trek: Deep Space Nine
In the Star Trek: Deep Space Nine season 5 episode "Dr. Bashir, I Presume?" the creator of the Emergency Medical Hologram, Dr. Lewis Zimmerman, arrived on the station with the intention of modeling the next generation of the technology, the Long-term Medical Hologram, on Dr. Julian Bashir (Alexander Siddig). In the process, Zimmerman's holographic incarnation, the EMH, also appeared in the episode, but it was, again, not the same character as the EMH in Star Trek: Voyager.
"Dr. Bashir, I Presume?" revealed that Julian was actually genetically-engineered, which threatened his Starfleet career. Meanwhile, Dr. Zimmerman became infatuated with Leeta (Chase Masterson), a Dabo Girl in Quark's Bar, and nearly convinced her to leave the station with him. However, the fact that the EMHs all resembled Dr. Zimmerman proved to be a clever way for Robert Picardo to appear in the other Star Trek shows and movies during the 1990s.
Tuvok In Star Trek: Deep Space Nine
The Mirror Universe version of Tuvok (Tim Russ) appeared in the Star Trek: Deep Space Nine season 3 episode "Through the Looking Glass". Mirror Tuvok was part of the Terran Rebellion against the Klingon-Cardassian Alliance in the alternate universe, although Tuvok was of a different faction from the one led by the Mirror version of Julian Bashir. Mirror Tuvok briefly appeared in a scene where Commander Benjamin Sisko (Avery Brooks), posing as the Mirror Captain Sisko, arrived and took command of the Rebellion.
Tuvok is the only Star Trek: Voyager character whose Mirror version appeared in a Star Trek episode since Voyager didn't deal with the Mirror Universe. Further, Tuvok is the only Mirror Universe version of a Star Trek character to appear outside of his own TV series. Star Trek: Voyager later revealed that Tuvok once served aboard the U.S.S. Excelsior commanded by Captain Hikaru Sulu (George Takei) during the Star Trek: The Original Series' era as well.
Icheb In Star Trek: Picard
Icheb (Casey King) appeared in the Star Trek: Picard episode "Stardust City Rag". In a flashback to 2385, Icheb was killed by Bjayzl (Necar Zadegan), a black marketeer who specializes in Borg parts. Icheb was captured by Bjayzl and had his Borg implants harvested. Seven of Nine arrived too late and Icheb died in her arms. Seven considered Icheb a son after they met when Icheb was a Borg child reclaimed by the crew of the U.S.S. Voyager. Icheb remained part of Star Trek: Voyager for the final two years of the series and he returned to Earth with the lost starship. Later, Icheb joined Starfleet and rose to become a Lieutenant and the Science Officer of the U.S.S. Coleman before he was captured and killed by Bjayzl.