(written from a Production point of view)
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 "Spock's Brain", a story in which Kara, 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 Up Till Now, William Shatner sarcastically calls the episode's plot a "tribute" to the top brass at NBC.) The cast also seemed to be unhappy with "The Way to Eden", in which the Enterprise was visited by a group of "space hippies".
Other episodes however continued to serve as political parables. "Day of the Dove" carried a strong anti-war message, while "Let That Be Your Last Battlefield" 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. "The Empath" 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. "Plato's Stepchildren" 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 "The Paradise Syndrome", 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 "Requiem for Methuselah", inadvertently bringing about her death. Spock attracted female attention in episodes like "The Enterprise Incident", "The Cloud Minders", and "All Our Yesterdays", and even McCoy and Scotty found love in "For the World is Hollow and I Have Touched the Sky" and "The Lights of Zetar", respectively.
Of the junior crewmembers, Chekov had significant roles in "Spectre of the Gun" and "The Way to Eden", the latter giving a rare insight into his past. Sulu was given a chance to command the ship in "Spock's Brain", for the first time since "Errand of Mercy", and accompanied Kirk and McCoy on an away team in "That Which Survives", while Uhura and Christine Chapel finally had an opportunity to get closer to the two leads in "Plato's Stepchildren", albeit at the behest of telekinetic aliens.
The Klingons made two major appearances in "Elaan of Troyius" and "Day of the Dove". The latter introduced the character of Kang, who was later seen in Star Trek: Deep Space Nine and Star Trek: Voyager. The Romulans appeared in person for the first time since "Balance of Terror" when they returned in "The Enterprise Incident", and the Tholians were introduced in "The Tholian Web". "The Savage Curtain" 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 "Turnabout Intruder", 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...
- Fred Freiberger - Producer
- Robert H. Justman - Co-Producer ("Spectre of the Gun" - "That Which Survives")
- Gene Roddenberry - Executive Producer
- Gregg Peters - Associate Producer
- Edward K. Milkis - Associate Producer
- Douglas S. Cramer - Executive in Charge of Production
- Gregg Peters - Unit Production Manager
- Arthur H. Singer - Story Consultant
- Walter M. Jefferies - Art Director
- John Dwyer - Set Decorator
- Jerry Finnerman - Director of photography ("Spectre of the Gun" - "The Empath")
- Al Francis - Director of photography ("The Tholian Web" - "The Way to Eden", "The Savage Curtain" - "Turnabout Intruder")
- John Finger - Director of photography ("Requiem for Methuselah" (uncredited))
- Gil Kissel - Assistant Director
- Claude Binyon, Jr. - Assistant Director
- Gene DeRuelle - Assistant Director
- Charles Washburn - Second Assistant Director
- Bill Brame - Film Editor
- Donald R. Rode - Film Editor
- William Ware Theiss - Costume Designer
- Fred B. Phillips - Make-Up Artist
- Pat Westmore - Hair Stylist
- George A. Rutter - Script Supervisor
- Joseph D'Agosta - Casting Director
- William J. Kenney - Casting Director
- Irving A. Feinberg - Property Master
- Jim Rugg - Special Effects
- Douglas H. Grindstaff - Sound Effects Editor
- Richard Lapham - Music Editor
- Gordon L. Day - Re-recording Mixer
- Carl W. Daniels - Production Mixer
- George H. Merhoff - Gaffer
- George Rader - Head Grip
- Mike May - Props
- Jud Taylor
- Some production staff members were disappointed with season three. In a 2006 interview, Leonard Nimoy called it "very weak in general, but it was especially not good for Spock." 
- Ira Steven Behr once said that both he and his sister were disappointed "with the third season". wbm
- For the third season, the title and credits were in a light blue color, much like the credits of Star Trek: The Next Generation.
- Kirk no longer wore a green wrap-around shirt in any of the episodes, though officers were seen wearing the full dress uniform in "Is There in Truth No Beauty?" and "The Savage Curtain". In the third season Scotty's dress uniform was accompanied by a traditional Scottish kilt. The uniforms were no longer made of velour (which shrank every time it was cleaned), but of double-knit polyester.
- Each episode of the third season now cost about US$180,000, the budget having been reduced even further. Consequently, only two episodes out of the 24 this season ("The Paradise Syndrome" and "All Our Yesterdays") featured location scenery.
- Gene Roddenberry was initially promised an early evening time slot (Mondays at 7:30 pm) by NBC. However, this would have required their top-rated series Laugh-In to be moved from its 8 pm time slot to 8:30. Laugh-In producer George Schaltter threatened to take his show to another network unless it was guaranteed the 8 pm slot. NBC capitulated, forcing Trek to air its third season in the only remaining slot on the schedule – Fridays at 10 pm. Roddenberry threatened to leave Star Trek entirely if it wasn't put back to the promised time slot, but NBC rejected his threats due to the show's low ratings. He technically kept the post of executive producer for this season, but had actually left for MGM to work on other projects.
- Because of Roddenberry's withdrawal, scripts were no longer revised or re-written by him, nor by either Gene L. Coon or D.C. Fontana, who both left the series earlier. Script quality greatly suffered because of this. (Inside Star Trek: The Real Story)
- After Roddenberry and most of the writing staff left after the second season, Fred Freiberger took over as producer, with Arthur Singer replacing D.C. Fontana as script consultant. According to Fontana, Singer came to the set one day, and asked "By the way, what does that transporter thing do again?" 
- Robert Justman was promoted to co-producer, but left the series after "Let That Be Your Last Battlefield". Gregg Peters became the new associate producer.
- A most important change was the departure of cinematographer Jerry Finnerman after "The Empath", and his replacement with his former camera operator, Al Francis, which affected the visual style of the series.
- Several new writers were brought in. Many of them were non-professionals, who sent in story outlines, which were read and recommended by Justman. These included Jean Lisette Aroeste, Joyce Muskat, and Judy Burns.
TOS Season 2
Star Trek: The Original Series
|Final season in series|