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Created by Gene Roddenberry, the science fiction television series Star Trek (which eventually acquired the retronym Star Trek: The Original Series) stars William Shatner as Captain James T. Kirk, Leonard Nimoy as Mr. Spock, and DeForest Kelley as Dr. Leonard "Bones" McCoy aboard the fictional Federation starship USS Enterprise. The series originally aired from September 1966 through June 1969 on NBC.
This is the first television series in the Star Trek franchise, and comprises 79 regular episodes over the series' three seasons, along with the series' original pilot episode, "The Cage". The episodes are listed in order by original air date, which match the episode order in each season's original, remastered, and Blu-ray DVD box sets. The original, single-disc DVD releases placed the episodes by production order, with "The Cage" on the final disc.
After the series' cancellation, Paramount Television released Star Trek to television stations as a syndication package, where the series' popularity grew to become a "major phenomenon within popular culture". This popularity would eventually lead to the expansion of the Star Trek catalog, which as of 2020 includes nine more television series and thirteen Trek motion pictures.
In 2006, CBS Paramount Domestic Television (now CBS Television Distribution) announced that each Original Series episode would be re-syndicated in high definition after undergoing digital remastering, including both new and enhanced visual effects. (To date, the remastered episodes have only been broadcast in standard definition, though all three seasons are now available on the high-definition Blu-ray Disc format.) The remastered episodes began with "Balance of Terror" (along with, in some markets, "Miri") during the weekend of September 16, 2006, and ended with "The Cage", which aired during the weekend of May 2, 2009. The remastered air dates listed below are based on the weekend each episode aired in syndication. and starred Jeffrey Hunter as Captain Christopher Pike, Majel Barrett as Number One, and Leonard Nimoy as Spock. The pilot was rejected by NBC as being "too cerebral" among other complaints. Jeffrey Hunter chose to withdraw from the role of Pike when creator Gene Roddenberry was asked to produce a second pilot episode "Where No Man Has Gone Before". A slightly edited version with the same title aired in 1966 as the third episode of the new series.
"The Cage" never aired during Star Treks original run. It was presented by Roddenberry as a black-and-white workprint at various science fiction conventions over the years after Star Treks cancellation but was not released on home video until 1986 when Paramount Home Video produced a "restored" release of "The Cage" (a combination of the original black-and-white footage and color portions of the Season 1 episode "The Menagerie") along with an introduction by Gene Roddenberry.
On October 15, 1988, Paramount Pictures aired a two-hour television special, hosted by Patrick Stewart, called The Star Trek Saga: From One Generation to the Next, which featured, for the first time, a full-color television presentation of "The Cage". It was later included on the final disc in both the original and "remastered" season 3 DVD box sets listed with its original air date of October 15, 1988.
"Where No Man Has Gone Before" in its original form (production number 02a) had been forwarded to NBC, but only a re-edited version was aired, not as a pilot but as the third episode of the series (production number 02b). The original version was thought to be lost, but later appeared on bootleg VHS tapes at conventions, until a print of it was discovered in 2009 and subsequently released on home video under the title "Where No Fan<!-- Fan is correct --> Has Gone Before" - The Restored, Unaired Alternate Pilot Episode as part of the TOS season 3 box set on Blu-ray; it has not been released on DVD.