Leonard Nimoy and William Shatner in 'Star Trek: The Original Series'

Best ‘Star Trek: The Original Series’ Episodes, Ranked

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Leonard Nimoy and William Shatner in 'Star Trek: The Original Series'
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Created by Gene Roddenberry, Star Trek: The Original Series premiered on NBC on September 8, 1966, and aired three seasons consisting of 79 episodes, many of them classics of sci-fi entertainment.

“You know. 1966? 79 episodes, about 30 good ones,” said Futurama’s Philip J. Fry to Leonard Nimoy, who’s alive in that universe as a head in a jar.

Of course, that’s Fry’s opinion. I would suggest watching all of them, but that’s not the assignment. So, read on for a list of the 15 best Star Trek: The Original Series episodes ranked.

15. “Tomorrow Is Yesterday” (season 1, episode 19)

Captain Christopher visits the bridge of the Enterprise with Captain Kirk in the episode "Tomorrow Is Yesterday"

In this episode, an encounter with a black hole sends the Enterprise to 20th-century Earth, where it is seen by an Air Force pilot, whose son has an important role to play in the future. Written by longtime Trek scribe D.C. Fontana, “Tomorrow Is Yesterday” is notable for being the first episode written solely by a woman. Although she had previously written the teleplay for “Charlie X,” Roddenberry received the writing credit.

14. “Plato’s Stepchildren” (season 3, episode 10)

Uhura and Kirk kiss; it's the first interracial kiss on television in 'Star Trek: The Original Series'

After Leonard McCoy (DeForest Kelley) saves a tyrannical king’s life, he uses torture to prevent him from returning to the Enterprise. From a feminist point-of-view, “Plato’s Stepchildren” isn’t the best Trek episode ever made due to this. Still, I’ve included it on this list as it was a culturally significant episode as the first interracial kiss between Black and White actors on scripted American television.

13. “Catspaw” (season 2, episode 7)

Spock and Kirk in shackles next to a skeleton in "Catspaw" in 'Star Trek: The Original Series'

“Trick or treat, Captain?” Yup, “Catspaw” is Trek‘s only Halloween episode. When the Enterprise discovers alien beings disguised as humanoids on Pyris VII, the aliens erect a haunted house—complete with a dungeon, eerie fog, witches, and black cat—to prevent Jim Kirk (William Shatner) from discovering their true plan: conquering the galaxy. Maybe you’ve heard this is one of the series’ worst episodes, but I think it’s spooktastic fun, written by Psycho novelist Robert Bloch.

12. “Operation — Annihilate!” (season 1, episode 29)

Spock, Kirk, and Scotty fire their phasers at organisms in "Operation -- Annihilate!" in 'Star Trek: The Original Series'

In “Operation — Annihilate!,” behavior-altering parasites cause mass hysteria, destroying the civilizations of several planets. When the Enterprise arrives at the Federation colony where Sam Kirk (Shatner) lives, it’s too late: Sam has already been pancaked. To kill the parasites without harming the hosts, McCoy devises a light treatment that he tests on Spock (Nimoy), causing the Vulcan to go blind temporarily. But, Vulcans are like cats and have inner eyelids, preventing Spock from going completely blind.

11. “The Cage” (first pilot)

Jeffrey Hunter as Captain Christopher Pike, Majel Barrett-Roddenberry as Number One, Laurel Goodwin – Yeoman J. M. Colt, and unknown Talosian actor in 'Star Trek: The Original Series'

In Trek‘s rejected pilot, “The Cage,” Christopher Pike (Jeffrey Hunter) and the Enterprise investigate an 18-year-old shipwreck and encounter a race of telepathic aliens, the Talosians, who want a human specimen for their menagerie. Although it included Spock and some core Trek themes, it also differed tremendously from what viewers saw in “Where No Man Has Gone Before.”

When CBS All Access ordered Star Trek: Strange New Worlds in May 2020, producer Henry Alonso Myers called it the longest pilot to series pick up in TV history in Paramount+’s YouTube video “Bringing A Series to Life.”

10. “The Naked Time” (season 1, episode 4)

George Takei and Nichelle Nichols in "The Naked Time" in 'Star Trek: The Original Series'

In this Hugo Award-nominated episode, while investigating the Psi 2000 research team’s deaths, the Enterprise crew becomes infected with a virus that provokes irrational and emotional behavior. Spock cries, Christine Chapel (Majel Barrett-Roddenberry) admits her love for Spock, and Hikaru Sulu (George Takei) threatens the bridge with his fencing foil, only to be foiled by a Vulcan nerve pinch (the first time one was seen onscreen).

In an interview, Takei told CJAD host Peter Anthony Holder that “without question,” his favorite episode was “Naked Time.”

9. “I, Mudd” (season 2, episode 8)

Captain Kirk with two android women in 'Star Trek: The Original Series'

“I, Mudd” is the Enterprise’s second encounter with Harcourt Fenton Mudd (Roger C. Carmel). In the episode, Norman (Richard Tatro), an android, masquerades as a crewmember, steals the ship and takes it to an unmapped planet, where the landing party finds King Mudd the First, proudly displaying the beautiful female androids created for human amusement. However, all is not what it seems; that twist makes this episode great.

8. “The City on the Edge of Forever” (season 1, episode 28)

Joan Collins and William Shatner in The City on the Edge of Forever in 'Star Trek: The Original Series'

Widely considered one of the best TOS episodes, “The City on the Edge of Forever” was penned by Harlan Ellison (although it went through several rewrites, much to his distaste). In the episode, a mentally compromised McCoy steps through a time portal into Depression-era NYC, changing history. Kirk and Spock then travel through the portal, hoping to prevent McCoy from altering the timeline. While waiting for him, Kirk meets a social worker, Edith Keeler (Joan Collins), and falls in love, only to learn that her life is the one McCoy saved to alter the timeline. Kirk must decide between the girl and the timeline. 

7. “The Devil in the Dark” (season 1, episode 25)

Spock mind melds with a an monster that looks like an orange blob while other members of Starfleet look on in 'Star Trek: The Original Series'

While investigating the deaths of Janus VI miners, the Enterprise discovers a new species, the Horta, and Spock mind melds with a nonhumanoid alien for the first time, learning the alien had been willing to share the planet until oblivious humans destroyed her eggs. With Spock as a mediator, the miners and the Horta can now communicate effectively and negotiate a treaty. The monster has changed in the miners’ eyes to a cute little devil, making the episode a great lesson in the dangers of stereotyping.

6. “Balance of Terror” (season 1, episode 14)

Mark Lenard as a Romulan Commander in "Balance of Terror" in 'Star Trek: The Original Series'

“Balance of Terror” is the first time Starfleet sees the Romulans and learns they look exactly like the Vulcans. When the Enterprise is alerted that a Romulan bird-of-prey has destroyed a Federation outpost guarding the Neutral Zone, Starfleet orders Kirk to destroy the ship. Meanwhile, the Romulan commander (Mark Lenard) is ordered by his people to do the same. Regularly topping best-of lists as a commentary on war and the prejudices it creates, the episode is notable for what the Romulan commander tells Kirk: “You and I are of a kind. In a different reality, I could have called you friend.”

5. “Space Seed” (season 1, episode 22)

Ricardo Montalban as Khan in Space Seed in 'Star Trek: The Original Series'

“Space Seed” is the first appearance of a longtime Kirk foe: Khan Noonien Singh (Ricardo Montalbán), a genetically engineered strongman and leader in Earth’s Eugenics War. The magnetism of Montalbán (not to mention his thick, thick chest) is worth the price of admission alone. The episode is also an essential story for Star Trek II: The Wrath of Khan, Star Trek: Strange New Worlds, and several Star Trek: Enterprise episodes.

4. “Arena” (season 1, episode 18)

A Gorn, a green lizard-like creature, battles Captain Kirk in 'Star Trek: The Original Series'

“Arena” features one of the most memorable TOS sequences, where Kirk fights a green lizard-like creature with glowing red eyes, wearing a gold, flower tunic. Although it’s a battle to the death, in the end, Kirk chooses mercy for his opponent over landing a killing blow—one of the enduring themes of Trek. Oscar-winner Wah Chang built the famous neoprene-latex lizard suit, now owned by Ben Stiller.

3. “Amok Time” (season 2, episode 1)

Arlene Martel as T'Pring in "Amok Time" in 'Star Trek: The Original Series'

In “Amok Time,” Spock reveals that to deal with powerful sexual urges—without emotion, of course—Vulcans are ritually wedded in childhood. Still, this sublimation isn’t enough to stop pon farr every seven years when Vulcan men must mate or die. Upon learning this, Kirk rushes Spock to Vulcan, where Spock learns that his fianceé T’Pring (Arlene Martel) wants to marry someone else.

An iconic episode, it was the first to use the Vulcan salute, introduce the concept of pon farr, and feature Pavel Chekov (Walter Koenig). Lastly, shout out to the late composer Gerald Fried: the music is as iconic as the episode itself, especially the music for the Vulcan kal-if-fee ritual.

2. “The Savage Curtain” (season 3, episode 22)

Uhura has to deal with a racist Abraham Lincoln in 'Star Trek: The Original Series'

“The Savage Curtain” opens with the Enterprise running scans on a strange planet, when Abraham Lincoln (Lee Bergere) appears on the viewscreen and comes aboard the ship. As the captain admires Lincoln, of whom he says, “I think of all our heroes on Earth, he is the most loved today,” the US president is racist to Uhura. What makes this episode interesting is that while it seems to discredit the myth of the American Civil War with Lincoln’s racism, it also perpetuates the myth of American nationalism by classifying him as “good.”

1. “Journey to Babel” (season 2, episode 10)

The first time Vulcans, Andorians, and Tellarites are onscreen together in 'Star Trek: The Original Series'

Written by the late, great Fontana, “Journey to Babel” may be one of her most iconic episodes. In it, the Enterprise is transporting a widely divergent group of ambassadors to the Babel Conference, including Spock’s parents, Sarek (Lenard) and Amanda (Jane Wyatt), relationships that were explored in-depth in Star Trek: Discovery. When the Tellarite Ambassador shows up murdered, Sarek becomes the center of the episode, showcasing how skillfully Fontana can navigate drama.

Also notable, the episode introduces Andorians and Tellarites.

(featured image; CBS)

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Rebecca Oliver Kaplan
Rebecca Oliver Kaplan (she/he) is a comics critic and entertainment writer, who's dipping her toes into new types of reporting at The Mary Sue and is stoked. In 2023, he was part of the PanelxPanel comics criticism team honored with an Eisner Award. You can find some more of his writing at Prism Comics, StarTrek.com, Comics Beat, Geek Girl Authority, and in Double Challenge: Being LGBTQ and a Minority, which she co-authored with her wife, Avery Kaplan. Rebecca and her wife live in the California mountains with a herd of cats.