After the original Star Trek live-action series went into syndication, demand for new adventures on the Enterprise hit a fever pitch. To continue the popularity of the show, Filmation teamed up with Gene Roddenberry for an animated series featuring most of the original cast voicing their corresponding characters (the exception was Checkov, who was cut due to budget constraints).

Though the show varied wildly in animation quality–the extensive use of stock shots was often cut with “near-theatrical quality” scenes–its popularity sustained the Star Trek universe until Star Trek: the Motion Picture was released in 1979.

A fun fact: The episode “The Practical Joker” (Season 2, Episode 3) features the first appearance of the Holodeck.

All 22 half-hour episodes are now available online at StarTrek.com, including the classic “More Tribbles, More Troubles” episode.