Star Trek: The Original Series produced some incredible episodes throughout its three-year run, making it difficult to narrow a best-of list down to 10. The Star Trek franchise has become a pop culture juggernaut, but it all began with the iconic adventures of Captain James T. Kirk (William Shatner), Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley). Gene Roddenberry depicted a utopian future where humanity's main goal had become exploration. While Roddenberry's vision may have been limited by the culture of the 1960s, Star Trek nevertheless presented a revolutionary and incredibly progressive view of the future.
Star Trek: The Original Series holds up well nearly 60 years after its premiere, thanks largely to the strength of its characters and stories. Characters like Chief Engineer Montgomery Scott (James Doohan) and Lt. Uhura (Nichelle Nichols) may not have gotten as much screen time as the main trio, but they became iconic in their own right. Star Trek has, of course, since become a massive franchise, with multiple universes and numerous films and television shows, but none of that would have been possible without Captain Kirk and his adventures aboard the USS Enterprise.
10 "A Piece of the Action"
Star Trek: The Original Series Season 2, Episode 17
When the Starship Enterprise visits the planet Sigma Iotia II, they find a society built around the culture of 1920s-era Chicago. As Kirk, Spock, and McCoy investigate the planet, they hilariously try to adapt to the local culture. Kirk and Spock don appropriate attire, speak with exaggerated gangster movie accents, and use language that the locals, including mob boss Bela Oxmyx (Anthony Caruso), will understand.
From Kirk's invented card game, Fizzbinn, to Spock's reticence to ride in a car with his captain, "A Piece of the Action" is one of Star Trek's funniest hours. Spock's witty humor and Leonard Nimoy's always-perfect delivery work particularly well here, and he and Kirk play off of one another perfectly. Not only does the episode address the importance of Starfleet's Prime Directive, but it also demonstrates Star Trek's ability to switch seamlessly between genres.
9 "The Galileo Seven"
Star Trek: The Original Series Season 1, Episode 16
It didn't take long after Star Trek: The Original Series premiered for Leonard Nimoy's Spock to become one of the show's most popular characters. As the show progressed, more and more episodes began to focus on Spock, and "The Galileo Seven" offers some fascinating insight into everyone's favorite Vulcan. When Spock leads a science team to investigate a quasar-like formation, the mission goes from bad to worse.
"The Galileo Seven" is a great vehicle for Spock as a character and tells an incredibly compelling story besides.
Aboard the shuttlecraft Galileo, Spock is forced to make an emergency landing on the foggy planet Taurus II. Before long, native ape-like creatures attack, killing two Enterprise crew members on Spock's watch. As Spock faces impossible decisions and insubordinate officers, he begins to realize that logic does not provide all the answers. "The Galileo Seven" is a great vehicle for Spock as a character and tells an incredibly compelling story besides.
8 "The Doomsday Machine"
Star Trek: The Original Series Season 2, Episode 6
When the Enterprise answers the distress call of the USS Constellation, they find the commander, Commodore Matt Decker (William Windom), to be the only survivor. Understandably distraught, Decker describes the massive planet-eating machine that killed his entire crew. Decker then takes command of the Enterprise and engages the machine, before ultimately sacrificing himself by flying a shuttle into the planet killer.
"The Doomsday Machine" is an effectively tense episode that builds to a nail-biting conclusion.
Kirk then explodes the Constellation inside of the doomsday machine, rendering the planet killer non-operational. Thanks to a striking score, a tight plot, and a compelling performance from William Windom, "The Doomsday Machine" is an effectively tense episode that builds to a nail-biting conclusion. The episode may not get as much recognition as some, but it nevertheless pops up frequently in best-of lists and more than deserves its place.
7 "Arena"
Star Trek: The Original Series Season 1, Episode 18
When the Enterprise pursues a Gorn ship that destroyed a Federation outpost, both ships end up in an area of space guarded by the powerful Metrons. The Metrons transport Captain Kirk and the Gorn captain to the surface of a barren asteroid and demand that they fight to the death. Kirk eventually manufactures a rudimentary cannon, but ultimately allows the Gorn to live, which impresses the Metrons.
Captain Kirk got into plenty of fights throughout his time as captain of the Enterprise, but his battle with the Gorn is his most famous. Kirk's ingenuity is on full display, as he realizes he cannot hope to beat the Gorn in direct hand-to-hand combat and then uses his environment to come up with creative solutions. "Arena" remains one of Star Trek's most memorable episodes, and Kirk's ultimate decision to show mercy to the Gorn exemplifies Star Trek's ideals.
6 "Space Seed"
Star Trek: The Original Series Season 1, Episode 22
When the Enterprise finds the SS Botany Bay drifting in space, they discover dozens of humans who have been in cryosleep for nearly 200 years. The group's leader is the infamous Khan Noonien Singh (Ricardo Montalbán), a genetically enhanced tyrant from the 20th century. Khan attempts to take over the Enterprise, but Kirk ultimately thwarts him and strands Khan and his people on the harsh but livable planet of Ceti Alpha V.
"Space Seed" is notable for introducing Khan, who would become the major antagonist in Star Trek II: The Wrath of Khan, one of the franchise's most celebrated films. But even without this factor, "Space Seed" is a solid episode that pits Kirk, Spock, and McCoy against a formidable foe who nearly beats them. The episode tackles the dangers of technology and hubris, while also presenting fun, sci-fi action and a fascinating guest star.
5 "Amok Time"
Star Trek: The Original Series Season 2, Episode 1
When Spock begins exhibiting signs of the Vulcan condition known as pon farr, the Enterprise travels to Vulcan so Spock can reunite with his fiancee, T'Pring (Arlene Martel). T'Pring, however, has fallen for another and demands kal-if-fee, a fight to the death between Spock and another champion — in this case, Captain Kirk. In the fight, Spock appears to kill Kirk and he renounces his bond with T'Pring. Upon traveling back to the Enterprise, Spock realizes that Dr. McCoy gave Kirk a neuroparalyzer that only made the captain appear dead.
Not only does "Amok Time" offer the first look at the planet Vulcan, but it also establishes several aspects of Vulcan culture that remain important in modern Star Trek. "Amok Time" is a strong episode for both Kirk and Spock, with the scene where Spock realizes Kirk is alive being a particular highlight. From fascinating alien cultures to dramatic battle scenes to heartwarming character moments, "Amok Time" delivers everything anyone could want in a Star Trek episode.
4 "The Trouble With Tribbles"
Star Trek: The Original Series Season 2, Episode 15
In another comedic episode, the Starship Enterprise visits Deep Space Station K7 to guard a shipment of grain. As Enterprise crew members enjoy shore leave on the station, a trader gives Lt. Uhura a tribble. Before long, Uhura's tribble has multiplied into hundreds of tribbles, and the little balls of fluff begin to overrun the Enterprise. With Klingon brawls, poisoning plots, and an increasingly annoyed Kirk, "The Trouble With Tribbles" remains just as funny today as it ever was.
"The Trouble With Tribbles" was nominated for a Hugo Award, but lost to season 1's "The City on the Edge of Forever."
"The Trouble With Tribbles" consistently lands on best-of lists and it contains some truly iconic and memorable Star Trek moments. The episode is genuinely hilarious while still being quintessentially Star Trek, offering clever dialogue and fun character moments. "The Trouble With Tribbles" is so beloved that Star Trek: Deep Space Nine revisited it in DS9 season 5, episode 6, "Trials and Tribble-ations" for Star Trek's 30th anniversary.
3 "Mirror, Mirror"
Star Trek: The Original Series Season 2, Episode 4
When the Enterprise transporter malfunctions, Captain Kirk, Dr. McCoy, Scotty, and Uhura find themselves aboard the ISS Enterprise in an alternate mirror universe. The ship belongs to the brutal Terran Empire, and torture and assassination are commonplace among the crew. As Kirk and his crew work to find a way home, they must impersonate their "evil" counterparts, but the Mirror Universe Spock (who sports a goatee) soon grows suspicious.
In the end, Mirror Universe Spock helps Kirk and his crew get home and promises Kirk that he will consider rising against the Terran Empire. Not only is "Mirror, Mirror" a great episode in and of itself, but it also introduces the Mirror Universe, which remains a part of the Star Trek universe even today. Almost all of the main crew members get something to do, and the reveal that Mirror Universe Spock is not all that different from the Spock viewers have come to love works particularly well.
2 "Balance Of Terror"
Star Trek: The Original Series Season 1, Episode 14
Known for introducing the Romulans, "Balance of Terror" follows a tense cat-and-mouse game that pits Kirk against one of Star Trek's most conniving species. Kirk and the Enterprise are nearly evenly matched with the Romulan Commander (Mark Lenard) and his ship, and both vessels take significant damage. "Balance of Terror" keeps the tension high throughout the story as Kirk and the Romulan Commander face off, and the events of the episode have ramifications that reverberate throughout the Star Trek universe.
In its season 1 finale, Star Trek: Strange New Worlds revisited the events of "Balance of Terror," exploring how things would have played out with Captain Christopher Pike (Anson Mount) in command of the Enterprise.
"Balance of Terror" opens with a wedding that gets interrupted, and the would-be-groom later becomes the only fatality of the stand-off with the Romulan ship. Not only does this give the episode a tragic ending (despite Kirk's triumph over the Romulans), but it also has much more impact than the death of an unnamed redshirt. With glimpses into both sides of a tense conflict, "Balance of Terror" remains one of Star Trek's finest hours.
1 "The City On The Edge Of Forever"
Star Trek: The Original Series Season 1, Episode 28
With one of Star Trek's most tragic and effectively told stories, it's no surprise that "The City on the Edge of Forever" is regularly cited as one of the franchise's best episodes. The episode follows Captain Kirk and Spock as they travel back in time to 1930s New York to search for a frenzied Dr. McCoy. "The City on the Edge of Forever" combines a classic time travel plot with a stunning love story that feels real and timeless despite playing out in less than an hour of television.
Kirk's love story with Edith Keeler feels more genuine than many of his other romances, making its tragic ending all the more heartbreakingly effective.
Kirk's love story with Edith Keeler (Joan Collins) feels more genuine than many of his other romances, making its tragic ending all the more heartbreakingly effective. Kirk understands that Edith must die to preserve the future, but that does not diminish the sting of losing her. Several Star Trek actors, including William Shatner and Leonard Nimoy, have cited "The City on the Edge of Forever" among their favorite Trek stories, and it was the only Star Trek: The Original Series episode that won both a Writers Guild of America Award and a Hugo Award.
