Star Trek: The Animated Series is an animated science fiction television series set in the Star Trek universe. The series was aired under the name Star Trek, but it has become widely known under this longer name (or abbreviated as ST:TAS or TAS) to differentiate it from the original live action Star Trek. It is also sometimes referred to as "The Animated Adventures."

The series was produced by Filmation and ran for two seasons, 1973 and 1974, airing a total of twenty-two half-hour episodes. It featured most of the original cast performing the voices for their characters, except for Pavel Chekov (Walter Koenig), who was omitted because the show's budget could not afford the complete cast. He was replaced by two animated characters who made semi-regular appearances: Lieutenant Arex, a member of a species which had three arms and three legs; and Lt. M'Ress, a female Caitian. James Doohan, and Majel Barrett, besides performing their characters Montgomery Scott and Christine Chapel, performed the voices of Arex and M'Ress, respectively.

Koenig was not forgotten and later wrote an episode of the series, becoming the first Star Trek actor to write a Trek story in the process.

It is generally assumed that the episodes in the series take place after the events of the Original Series, possibly during the last year of the NCC-1701's five-year mission. However this is never stated on screen. It is impossible to support this notion using the stardates mentioned in the episodes, since they are often inconsistent with the Original Series. One episode, "Magicks of Megas-Tu" carries a stardate lower than that of the second pilot of the Original Series ("Where No Man Has Gone Before"); however, McCoy, who wasn't a member of the crew at the time of that early episode, is present. Another episode carries a stardate higher than that given in Star Trek: The Motion Picture which takes place approximately one and a half to two years after the events of the five-year mission.

As is usual for animation, the voice actors did not perform together but recorded their parts separately to avoid clashing with other commitments. For instance, William Shatner, who was touring in a play at the time, would record his lines in whatever city he happened to be in and have the tapes shipped to the studio. Doohan and Barrett, besides providing the voices of their Original Series characters and newcomers Arex and M'Ress, performed virtually all of the "guest star" characters in the series, except for a few notable exceptions such as Sarek, Cyrano Jones and Harcourt Fenton Mudd, who were performed by their original actors from The Original Series. Occasional other guest voice actors were also used, such as Ed Bishop (Commander Straker on UFO) who voiced the Megan Prosecutor in "Magicks of Megas-Tu", and Ted Knight (Ted Baxter on The Mary Tyler Moore Show) who voiced Carter Winston in "The Survivor".

While the freedom of animation afforded large alien landscapes, budget constraints were a major concern and the animation quality was generally fair, with very liberal use of stock shots. There were also occasional mistakes, such as characters appearing on screen who were elsewhere, or a character supposed to appear on the bridge main screen appears in front, indicating bad ordering of animation plates. These were typically one-off errors however. Occasionally, though, parts of episodes would be animated at a near-theatrical quality level.

All the episodes of this series were novelized by Alan Dean Foster and released in 10 volumes under the Star Trek Logs banner. Initially, Foster adapted three episodes per book, but later editions saw the half-hour scripts expanded into full novel-length stories.

The 22 episodes of TAS were spread out over two brief seasons, with copious reruns of each episode.

- From Wikipedia