TOS Season 3 Summary . With " Star Trek " having narrowly avoided cancellation , the basic format remained the same as Season 2 . Kirk , Spock , and McCoy were still the only characters to be given a regular credit , although Scotty also appeared in every episode . The season opened with , a story in which , the priestess - leader of the underground Eymorg city , steals Spock ' s brain and transfers it to a receptacle so that he can rule their society . Behind the scenes changes resulted in the season being poorly received by many fans and cast members . The season opener was based around the unlikely premise of Spock ' s brain being removed and then reattached without any adverse effects , which received much derision . ( In his 2008 autobiography , William Shatner sarcastically calls the episode ' s plot a " tribute " to the top brass at NBC . ) The cast also seemed to be unhappy with , in which the " Enterprise " was visited by a group of " space hippies " . Other episodes however continued to serve as political parables . carried a strong anti - war message , while dealt with racial hatred , ending with the " Enterprise " unable to prevent the destruction of a civilization or even dissuade the two survivors from continuing their feud . dealt well with new budget restrictions , telling a tightly constructed morality play with minimal sets and characters as Kirk , Spock , and McCoy teach an alien woman the value of self - sacrifice . may not have featured television ' s first interracial kiss as is often claimed , but was still groundbreaking enough to be banned in some states . Kirk had one of his most significant romances in , one of the longest " Star Trek " episodes in terms of fictional time , as he spent three months stranded on a planet , fell in love , and married , only for his pregnant wife to be killed in a tragic misunderstanding . He also fell in love with an android in , inadvertently bringing about her death . Spock attracted female attention in episodes like , , and , and even McCoy and Scotty found love in and , respectively . Of the junior crewmembers , Chekov had significant roles in and , the latter giving a rare insight into his past . Sulu was given a chance to command the ship in , for the first time since , and accompanied Kirk and McCoy on an away team in , while Uhura and Christine Chapel finally had an opportunity to get closer to the two leads in , albeit at the behest of telekinetic aliens . The Klingon s made two major appearances in and . The latter introduced the character of Kang , who was later seen in and . The Romulan s appeared in person for the first time since when they returned in , and the Tholian s were introduced in . saw Kirk and Spock forced to play out the battle against good and evil , with three of the other participants , Colonel Green , Kahless , and Surak , reappearing in later series . The episode also marked the last appearance of Uhura on the show . The season closed with , in which Kirk found himself trapped in the body of bitter former lover Janice Lester , who proceeded to charge his comrades with mutiny . Although it provided little of a sense of closure , it was a strong enough note for the show to go out on , and , although no one knew it at the time , the adventures of the crew of the " Enterprise " were far from over . . .