"Tuvix" is the 40th episode (24th in the second season) of the science fiction television program Star Trek: Voyager. The episode originally aired on May 6, 1996, and tells the story of Tuvok and Neelix being merged into a unique third character named Tuvix.
The episode was substantially rewritten from its original incarnation as a lighthearted story to a more somber tale with serious moral and ethical implications. Tom Wright guest stars as Tuvix to lend more credence to a unique new character that consists of equal parts Tuvok and Neelix. Both director Cliff Bole and Wright himself had reservations about the latter's take on the character, and despite a perceived lack of support, Wright still praised the Voyager cast and crew. Both the story and performances of "Tuvix" were lauded by the production team and critics alike.
Researchers and critics found "Tuvix" teeming with technical and philosophical content, including thematic ties to other episodes in the Star Trek canon, real-world logical and metaphysical ramifications, and scientific concessions for the story. "Tuvix" was well received by fans and television critics, earning approval ratings between 75–80%; the Tuvix character and Janeway's forced separation of the same were particularly polarizing among the episode's audience and distinguishes the episode for the copious feedback it generated.