10 Star Trek: The Original Series Episodes Everyone Should Watch

You don’t need to watch all 79 episodes of the original Star Trek to get the experience. These 10 episodes are the best introduction to the show. Created by Gene Roddenberry, this hopeful and forward-thinking science fiction series first aired on NBC in 1966. Though it only lasted three seasons before being canceled, passionate fans kept Star Trek alive through syndication in the 1970s.

Often called “The Original Series,” Star Trek is a landmark achievement in American television and heavily influenced countless science fiction shows that came after it. Its hopeful message of peace and acceptance resonated deeply with audiences during the challenging 1960s. Although it only lasted three seasons, Star Trek created a substantial collection of episodes that might seem overwhelming to those discovering it today.

Watching all 79 episodes of the original Star Trek series can be really satisfying, but it’s not essential, especially if you’re a casual fan. While many episodes are classics, others aren’t very memorable – or aren’t good at all. A curated list of the best episodes is a great way to experience the adventures of Captain Kirk and the crew of the Enterprise.

Here’s a list of 10 episodes that really capture the heart of the show. These aren’t just the best ones overall – they showcase the core ideas of Star Trek. They helped launch the entire 60-year-plus franchise and continue to resonate with viewers today. The episodes are listed in the order they originally aired, not by how good they are.

10. “Balance Of Terror” – Season 1 Episode 14

The first essential episode of the original Star Trek series is “Balance of Terror,” which appears as the fourteenth episode in season one. When the Enterprise faces a series of attacks from the Romulans, the crew begins to notice a remarkable resemblance between Spock and the enemy. This episode successfully blends suspense with compelling drama.

This episode is significant not only because it introduces a memorable Star Trek villain, but also because it reveals the crew’s weaknesses in a surprisingly believable way, challenging the optimistic ideals often presented in Star Trek. It even touches on political themes that remain relevant today. Beyond all that, it’s simply one of the most exciting episodes of the original series.

9. “Arena” – Season 1 Episode 18

Often called “The Gorn Episode,” “Arena” is a standout from the first season of Star Trek. It features a thrilling duel between Captain Kirk and the captain of a Gorn ship, forced to fight to the death on a dangerous planet. The episode is famously filmed at the striking Vasquez Rocks, perfectly setting the stage for an action-filled adventure.

Even with its focus on action, “Arena” stays true to the hopeful spirit of the series. In many ways, it perfectly demonstrates Captain Kirk’s true character, revealing what lies beneath his confident exterior. Beyond its philosophical depth, “Arena” is also a thoroughly enjoyable science fiction adventure, complete with a delightfully campy design for the Gorn.

8. “Space Seed” – Season 1 Episode 22

Khan Noonien Singh is arguably the most memorable one-on-one villain in the history of Star Trek, first appearing in the season 1 episode “Space Seed.” In this episode, the Enterprise finds and revives Khan, a genetically engineered dictator from the 20th century, who then attempts to seize control of the ship. “Space Seed” is important because it served as the foundation for the later film, Star Trek II: The Wrath of Khan.

This episode is a fantastic, suspenseful story on its own. Khan is a perfect match for Kirk, and their battle of intelligence is truly captivating. Though mostly set aboard the Enterprise, it’s consistently engaging. “Space Seed” explores complex science fiction ideas while ultimately telling a very human story about conflict and overcoming challenges.

7. “The Devil In The Dark” – Season 1 Episode 25

Despite seeming simple, the Star Trek episode “The Devil in the Dark” (season 1, episode 25) is incredibly important. When Kirk and Spock investigate a distress signal on a mining planet, they encounter a unique creature living underground that’s been attacking the miners. Before this episode, most aliens in Star Trek looked very similar to humans.

“The Devil in the Dark” first explores an idea that becomes central to the entire series: the incredible variety of life found throughout the galaxy. The Horta, a fascinating alien creature, is presented in a conflict that’s handled with intelligence and mystery. For a science fiction show from the 1960s, it tackles surprisingly complex themes.

6. “The City On The Edge Of Forever” – Season 1 Episode 28

Many fans consider “The City on the Edge of Forever” to be the best episode of the original Star Trek series. In this Season 1 episode, Kirk, Spock, and McCoy travel through a wormhole and find themselves in the 20th century. Their time travel alters the past, and they must fix it, even if it means making difficult sacrifices. Unlike some of the show’s more lighthearted moments, this episode is a serious and dramatic story.

While Star Trek’s time travel stories are often hit or miss, “City on the Edge of Forever” is a true masterpiece. This exceptional episode, written by renowned science fiction author Harlan Ellison, is a moving and unforgettable story. It’s widely considered the best Star Trek episode ever made and is essential viewing, even if you’re not a fan of the series.

5. “Amok Time” – Season 2 Episode 1

The second season of Star Trek begins with the powerful episode “Amok Time,” which delves into Vulcan customs. Spock experiences Pon Farr, a dangerous mating drive, and is forced to return to his homeworld for a traditional marriage ceremony. The episode is remembered for its memorable music and unique setting, and is considered a highlight of the series.

“Amok Time” is a standout episode of Star Trek: The Original Series because it dedicates significant time to exploring a non-human culture, unusually shifting the focus away from the human crew. Beyond its cultural exploration, the episode deepens Spock’s character and adds complexity to his connection with Starfleet and his fellow humans. It’s far more than a simple, contained story – it’s an episode you won’t want to miss.

4. “Mirror, Mirror” – Season 2 Episode 4

The Star Trek series revisited the alternate reality introduced in “Mirror, Mirror” many times, but the second-season episode remains the most compelling. It features Captain Kirk being accidentally transported to a parallel universe where the Federation is a ruthless empire built on cruelty. By this point in the show’s run, Star Trek understood its own ideals, and “Mirror, Mirror” cleverly flips those ideals on their head.

As a total film buff, I have to say, the little details in “Mirror, Mirror” – the slightly different costumes, the hilariously fake mustaches – are just charming. But honestly, it’s the writing that really makes the episode. So many Star Trek episodes fumble promising concepts, but this one takes a fairly basic premise and elevates it to something brilliant. It’s when the show asks those fascinating “what if?” questions that it truly hits its stride, and this episode is a perfect example.

3. “The Doomsday Machine” – Season 2 Episode 6

The Cold War and fears of nuclear annihilation heavily influenced the 1960s, and the Star Trek episode “The Doomsday Machine” cleverly plays on those anxieties. The Enterprise crew finds the remains of the Constellation and rescues a desperate commodore determined to destroy the weapon that decimated his ship. The true threat isn’t the machine itself, but the overwhelming anger that built it and continues to fuel its destructive path.

“The Doomsday Machine” is a classic Star Trek episode that’s both exciting and thought-provoking – a combination the show consistently pulls off. It reinforces Star Trek‘s message about the dangers of violence, while also highlighting how destructive hatred and the desire for revenge can be. The Doomsday Machine itself is a remarkably creative invention and showcases the incredible imagination of the show’s writers.

2. “Journey To Babel” – Season 2 Episode 10

Diplomacy is central to the world of Star Trek, and the episode “Journey to Babel” (season 2, episode 10) perfectly illustrates this. The Enterprise is tasked with carrying important representatives to a conference, but things get complicated when Spock’s father falls ill during the voyage. This episode also introduces two key alien races – the Tellarites and Andorians – who, along with Vulcans and Humans, were the original founders of the Federation.

“Journey to Babel” is a cleverly plotted and engaging episode of The Original Series, full of political maneuvering. It skillfully juggles multiple storylines, making for a rich and complex narrative. Beyond its importance in establishing key elements of the series, it remains one of the most enjoyable episodes to watch.

1. “The Trouble With Tribbles” – Season 2 Episode 15

I’ve always loved Star Trek: The Original Series, and while it’s known for tackling serious themes, it definitely wasn’t afraid to be funny! One of my favorite episodes is from Season 2, “The Trouble with Tribbles.” It’s just a delightful romp where the Enterprise is carrying vital supplies and gets completely swarmed by these adorable, rapidly multiplying, and incredibly hungry little creatures. It’s a really fun, lighthearted episode and a welcome change of pace from some of the show’s more intense storylines.

“The Trouble with Tribbles” offers a fresh perspective on our favorite characters while still delivering a smart and engaging story. It’s widely considered one of the best episodes of the original Star Trek series and is highly recommended for all television enthusiasts. While science fiction isn’t always for everyone, this episode is an exception.

2026-05-24 02:21