which production company produced the previously mentioned series?
Desilu Productions
Star Trek
In early 1964, Roddenberry presented a brief treatment for a television series to Desilu Productions, calling it "a "Wagon Train" to the stars." Desilu worked with Roddenberry to develop the treatment into a script, which was then pitched to NBC.

who was almost cast in star trek tos UNANSWERABLE the trouble with tribbles is it a film or series? It is the  fifteenth episode of the of the American science fiction television series "". fifteenth episode of which series? "Star Trek" episode who created this series? Gene Roddenberry. who is the aforementioned person? An American television screenwriter, producer and creator
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Star Trek [SEP] The "Original Series" era (1965–1969)
Unhappy with the show's ratings, NBC threatened to cancel the show during its second season. The show's fan base, led by Bjo Trimble, conducted an unprecedented letter-writing campaign, petitioning the network to keep the show on the air. NBC renewed the show, but moved it from primetime to the "Friday night death slot", and substantially reduced its budget. In protest, Roddenberry resigned as producer and reduced his direct involvement in "Star Trek", which led to Fred Freiberger becoming producer for the show's third and final season. Despite another letter-writing campaign, NBC canceled the series after three seasons and 79 episodes.