Star Trek: 10 Alien Races That Only Appeared Once
4. Kzinti
Mentioned in the Picard episode Nepenthe, the Kzinti have passed into Star Trek lore thanks to their one and only appearance in The Animated Series' The Slaver Weapon.
Their striking pink outfits were a key part to their lasting endearment with fans, in an encounter that was without Kirk for the first time ever. The Kzinti were a product of the opportunities that could be done with animation back in the 1970's but we’re not possible in live action. Today both are more than feasible and could lead to a return of this popular feline alien race.
For a group that was only in one episode of The Animated Series they certainly struck a chord with fans, however their background is still quite unclear leaving a lot of open ground for future writers. In comparison to humanity, their timeline is somewhat messy, with First Contact's warp flight causing all sorts of issues in relation to their apparent war with humanity pre-warp.
Interestingly this war is also the reason that the Kzinti are not allowed to possess weapons although Riker's concerns, enough to raise the household shields, suggests otherwise.