10 Best Episodes Of Star Trek: The Original Series Season 2, Ranked

Star Trek: The Original Series season 2 delivered just as many iconic episodes as the show's first season. By its second season, TOS had established its characters, as well as many elements of the Star Trek universe, from Starfleet to the Klingons. The show had figured out how well Captain James T. Kirk (William Shatner), Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley) worked as a trio, and many season 2 episodes emphasize this. This season also leans into humor a bit more than the first season, delivering some of Star Trek's funniest moments.

Star Trek: The Original Series season 2 also introduces several things that remain a part of the Star Trek franchise today. The season premiere, "Amok Time," establishes certain aspects of Vulcan culture, while the later "Journey to Babel" introduces Spock's parents. "Mirror, Mirror" introduces the Mirror Universe, and "Metamorphosis" reveals Zefram Cochrane (Glenn Corbett) as the inventor of the warp drive. Every subsequent Star Trek series, from Star Trek: The Next Generation to Star Trek: Prodigy, uses elements that debuted in TOS season 2.

10"A Private Little War"

Star Trek: The Original Series Season 2, Episode 19

In "A Private Little War," Captain Kirk faces a difficult decision after discovering that the Klingons have provided firearms to villagers on one side of a conflict. Having visited the planet before, Kirk has a friend among the villagers named Tyree, who is the leader of the opposing side. When Kirk is injured by a creature called a mugato, Tyree's wife, Nona (Nancy Kovack), treats him but is later killed.

According to the Star Trek 30 Years anniversary magazine, this episode was meant as an allegory for the ongoing Vietnam War.

Although Tyree was initially reluctant to use firearms, he now demands weapons from Kirk so that he can avenge his wife's death. Kirk provides a hundred flintlock pistols to the villagers but wonders if he has made the right decision. Kirk's choice is not a very Star Trek decision, but it makes for an interesting dilemma and compelling social commentary.

9“The Immunity Syndrome”

Star Trek: The Original Series Season 2, Episode 18

"The Immunity Syndrome" begins with Spock sensing the death of every member of the completely Vulcan crew of the USS Intrepid. When Captain Kirk takes the Enterprise to investigate the ship's last known location, crew members suddenly begin falling ill. Eventually, the cause is revealed to be a giant space amoeba. Spock and Dr. McCoy both volunteer for the possible suicide mission to venture into the creature to learn how to destroy it.Kirk ultimately chooses Spock for the mission, and the Enterprise successfully destroys the amoeba. "The Immunity Syndrome" may not be a particularly groundbreaking episode of Star Trek, but it delivers a tense story with some great character moments. The episode has some particularly good moments between Spock and Dr. McCoy, played wonderfully by Leonard Nimoy and DeForest Kelley.

8"Return To Tomorrow"

Star Trek: The Original Series Season 2, Episode 20

When the Enterprise visits a lifeless planet, they find three incorporeal beings who transfer their consciousnesses into Captain Kirk, Spock, and crewmember Dr. Ann Mulhall (Diana Muldaur). The being named Henoch tries to betray everyone in order to keep Spock's body, but the being named Sargon manages to stop him. Sargon and the third being, Thalassa, eventually agree to move on after sharing a kiss through Kirk and Mulhall.

The storyline gives Leonard Nimoy and William Shatner the chance to portray different characters.

"Return To Tomorrow" is one of many Star Trek episodes that includes god-like beings who have become corrupt because of their power. The storyline gives Leonard Nimoy and William Shatner the chance to portray different characters, and both actors seem to be having fun. In particular, it's fun seeing Spock show such strong emotions, and Diana Muldaur is also great in her Star Trek debut.

7"The Ultimate Computer"

Star Trek: The Original Series Season 2, Episode 24

Captain Kirk and his crew dealt with multiple rogue computers throughout Star Trek: The Original Series, and "The Ultimate Computer" offers a compelling take on this story. Dr. Richard Daystrom (William Marshall) comes aboard the Enterprise to install his new computerized M-5 Multitronic System, which will automate all the ship's systems. M-5 performs well in a training drill but then begins attacking other Federation starships.

Daystrom also invented the computer systems used by the Enterprise, and one of the Federation's most important research stations, The Daystrom Institute, was named after him.

In the end, Kirk talks the computer into shutting itself down, ultimately proving that the human equation cannot be completely replaced by computers. Early in the episode, Kirk worries that he will be replaced by the computer, a fear that remains relevant today regarding artificial intelligence. "The Ultimate Computer" is an intense episode with a strong guest star and a classic Star Trek story.

6"Journey To Babel"

Star Trek: The Original Series Season 2, Episode 10

A particularly influential episode of Star Trek, "Journey to Babel" introduces Spock's parents, Ambassador Sarek (Mark Lenard) and Amanda Grayson (Jane Wyatt). The episode follows the Enterprise as it transports several important dignitaries to a conference on the planet Babel. When one of the dignitaries is murdered, Sarek becomes the main suspect, and the stress causes him to have a cardiac event that requires a blood transfusion from Spock.

With a murder mystery and a medical emergency, "Journey to Babel" has a little bit of everything and offers fascinating insight into Spock's family. The episode also introduces the Andorians and the Tellarites, and it reveals more about the United Federation of Planets and its politics. "Journey to Babel" has some tense moments as an injured Kirk works to find the assassin and has some great character moments for the main trio.

5"A Piece Of The Action"

Star Trek: The Original Series Season 2, Episode 17

In one of Star Trek's funniest episodes, the USS Enterprise visits a planet called Sigma Iotia II with a culture based on the mob culture of 1920s-era Chicago. Kirk, Spock, and McCoy soon get caught in a power struggle between two rival gangs, and they must get creative to get out of their predicament. Kirk engineers a plan, using the Enterprise's weapons to convince the Iotians that the Federation is taking over the planet.

In a particularly hilarious scene, Kirk distracts their captors by inventing a card game called "fizzbin" with complicated and nonsensical rules.

Spock also gets some humorous moments, such as when he criticizes Kirk's driving ability and gets into character by talking like a mob boss. "A Piece of the Action" may not offer any profound commentary on what it means to be human, but it's an incredibly fun hour of television that puts Leonard Nimoy and William Shatner's considerable talent for comedy on full display.

4"The Doomsday Machine"

Star Trek: The Original Series Season 2, Episode 6

In "The Doomsday Machine," a trail of destroyed star systems leads the Enterprise to the heavily damaged USS Constellation, with the ship's captain as the only surviving crew member. The ship's commander, Commodore Matt Decker (William Windom), then takes over command of the Enterprise and attempts to take on the planet killing doomsday machine. Decker eventually sacrifices himself in a suicide run, giving Captain Kirk the idea that leads to the destruction of the planet killer.

From some great Kirk, Spock, and McCoy moments to a compelling story, "The Doomsday Machine" has everything that makes Star Trek great. It's a tense episode with a compelling and tragic guest star, but the story still has moments of humor and heart. The episode was nominated for a Hugh award in 1967 and regularly ranks among the top ten episodes of Star Trek: The Original Series (as do all of the top five episodes on this list).

3"Amok Time"

Star Trek: The Original Series Season 2, Episode 1

When Spock begins behaving strangely, the Vulcan eventually reveals that he is undergoing pon farr and must return to Vulcan. Captain Kirk risks his career to travel to Vulcan, where Spock prepares to marry his Vulcan fiancée, T'Pring (Arlene Martel). T'Pring, however, has other ideas and demands the kal-if-fee, forcing Spock and Kirk to engage in a battle to the death. In the end, Dr. McCoy fakes Kirk's death long enough for Spock to win the challenge.

As revealed in Star Trek: Strange New Worlds, Spock (Ethan Peck) and T'Pring (Gia Sandhu) were involved in a relationship prior to the events of "Amok Time" but broke things off.

"Amok Time" not only offers insight into Spock's background and Vulcan culture but also delivers a compelling story in its own right. Kirk's fight with Spock is one of Star Trek's most iconic battles, and Spock's joy when he realizes that Kirk is alive is a defining moment for the Vulcan. As if "Amok Time" weren't already influential enough, the episode also contains the first instance of the Vulcan salute and the phrase "Live long and prosper."

2"The Trouble With Tribbles"

Star Trek: The Original Series Season 2, Episode 15

When the Enterprise travels to a space station to guard a gain shipment, the crew encounters an adorable new alien called a Tribble. As purring balls of fluff, the Tribbles seem innocuous enough, but their rapid reproductive rate soon has the Starship Enterprise overflowing with the little creatures. Between conflicts with the Klingons and a conspiracy to poison the grain, "The Trouble with Tribbles" has some of Star Trek's most recognizable moments.

"The Trouble With Tribbles" illustrates how funny Star Trek can be when it leans into the more ridiculous elements of space exploration. Everyone involved delivers a solid performance, and the episode is one of Star Trek's most rewatchable entries. The scene where Captain Kirk is buried in Tribbles remains one of the show's funniest moments, as William Shatner proves his comedic chops yet again.

1"Mirror, Mirror"

Star Trek: The Original Series Season 2, Episode 4

When the transporter malfunctions, Captain Kirk, Dr. McCoy, Chief Engineer Scotty (James Doohan), and Lt. Uhura (Nichelle Nichols) all end up in a dark alternate universe that has come to be known as the Mirror Universe. Kirk and his friends pose as their Mirror Universe counterparts as they try to find a way back home, all while avoiding assassination attempts and punishment in the dreaded agonizer. Before long, Mirror Universe Spock begins to suspect the truth about Kirk and his crew members.

"Mirror, Mirror" remains one of the best episodes of Star Trek: The Original Series.

After initiating a mind meld with Dr. McCoy, Spock helps send the landing party back to their own universe. Not only does "Mirror, Mirror" introduce a major Star Trek staple with the concept of the Mirror Universe, but it also delivers a compelling story on its own. Illustrating Kirk's cleverness and Spock's adherence to logic in any universe, "Mirror, Mirror" remains one of the best episodes of Star Trek: The Original Series.