10 Essential Star Trek: The Animated Series Episodes You Must See
1. Yesteryear
The Guardian of Forever, Spock, Mark Lenard back as Sarek, and a sehlat. Need I go on? Yesteryear is undoubtedly the best The Animated Series had to offer, regularly cited as such, and merits a place amongst the finest episodes of Star Trek full stop. Written by the incomparable D.C. Fontana, Yesteryear adopts the tried-and-tested Trek time travel technique to tell a particularly poignant story about Spock's childhood.
The episode was the first on screen appearance of fanged "fat teddy bear"-esque Vulcan creature the sehlat (in domesticated form as Spock's pet I-Chaya), an animal only previously mentioned in passing in The Original Series episode Journey to Babel (much to the amusement of Doctor McCoy)
When it came to creating the look of the sehlat for its first appearance in Yesteryear, existing fan drawings from the Spockanalia fanzine were used by illustrators at Filmation. A distinctly less friendly wild CGI sehlat would then chase T'Pol and Archer in Star Trek: Enterprise's The Forge.
*Spoiler alert*
Unfortunately, I-Chaya was not long for Vulcan, having been fatally poisoned whilst protecting his master. What came next was pet euthanasia… on 'children's television'! According to Fontana, this had broadcaster NBC nervous, until Gene Roddenberry stepped in to say, "trust Dorothy".
In fact, the episode received not a single letter of complaint. As related in the documentary series The Center Seat: 55 Years of Star Trek, parents actually called NBC to thank them for addressing such a difficult subject on Saturday morning television.