Larry Niven brings the Kzinti to the Trek universe, and it's awesome! The TOS Rewatch discovers "The Slaver Weapon."
I like the intelligent conversations among the landing party about history and archaeology and the doping out of the weapon. I like the way Spock tries to play the Kzinti, and only partially succeeds (for starters, Chuft Captain knows that Uhura is intelligent, and so Spock’s hope that they won’t notice her turns out to be a forlorn one). And I like the fact that this story actually works perfectly in the half-hour format. Too many of the animated episodes either have too little or too much story for the running time, but this one is just right.