‘Star Trek’: 20 Greatest Episodes from the Original Series

"Spectre of the Gun"

"We had bee spending too much money by the network's reckoning, so we had less to spend on this particular episode," recalls Walter Koenig of the hour, which saw an away team forced to battle in an Old West-style gunfight. "It gave my character some interesting work. He got the girl, he died and came back to life. I loved the whole concept." 

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"The Galileo Seven"

Not only does this episode give us the first appearance of a shuttlecraft in Trek lore, it introduces a version of the concept that would become key to the franchise decades later — that there is a push and pull between the needs of the many and the needs of the few. The Enterprise is on a mission to deliver relief supplies to a colony. Meanwhile, seven crewmembers — including Spock and Bones — crash land on a hostile planet, and Kirk must grapple with holding out hope for them and delivering the relief supplies. 

"A Taste of Armageddon"

"This was the first Original Series episode I ever saw and it still blows my mind," says Jordan Hoffman, U.S. Film Critic for The Guardian and host of ENGAGE: The Official Star Trek Podcast. "Kirk is escorting a diplomat to a system of planets that have been in conflict for centuries. However, to protect their society’s infrastructure and maintain their culture, they don’t fight with weapons. Computers determine where phantom missiles hit and if your number comes up, you are ordered into a disintegration chamber. It is up to the Enterprise to intervene (which they totally aren’t supposed to do) and stop this insanity. It’s a rich concept with thrills, action, great speeches and even some humor. (Indeed, Spock takes the time to make a solid joke before sending someone crumpled to the floor with his Vulcan nerve pinch.)"

"The Doomsday Machine"

If Star Trek had shown Starfleet at its best until now, audiences got to see the flipside in this episode, in which Commodore Matt Decker (William Windom) turns into an outer space Ahab chasing the cosmic Moby Dick of the episode's title: a "planet killer" that had nearly destroyed his own ship and killed everyone on board except for him. For an episode with such stakes, it's a surprisingly subtle story: While we should be worried about whether the planet killer can be stopped, the real tension comes from watching Decker struggle to deal with his trauma. 

"The Corbomite Maneuver"

The first episode to be filmed after the two different pilots for the series, "Corbomite" manages to sum up everything that makes the original series so special, with a tense yet optimistic take on the idea of first contact between the Enterprise and an alien race that shows how fearless, compassionate and sneaky Captain James T. Kirk can be when pressed, and a Twilight Zone-esque last-second twist. As if that wasn't enough to make this episode worthwhile, it features the first times that DeForest Kelley and Nichelle Nichols played McCoy and Uhura — although by the time the episode aired, they were well-established characters to the loyal audience.

"Journey to Babel"

"I've always loved 'Journey to Babel,' by Dorothy Fontana," says writer David Gerrold when asked about his favorite Star Trek episode. "Because it reveals so much about Spock, and his past, and his parents." That's putting it mildly; before this episode, it's unlikely that anyone would have given much thought about the parents of any of the crew, but the introduction of Spock's estranged parents — one of whom was human, the other suspected of murdering a fellow diplomat on board the Enterprise — changed the way audiences looked at the characters forever: suddenly, they were more than just their jobs, and had inner lives and struggles that everyone could relate to. And all because the most alien of all of the crew had proven himself to be just as human as the rest of us.

"All Our Yesterdays"

While the final episode of the original series — "Turnabout Intruder" — is generally considered to be a low point for the show, the second last episode throws Spock, McCoy and Kirk back in time and puts them all out of their comfort zones as a result, with McCoy having to be the practical one, Spock becoming overwhelmed by emotions and Kirk on his own against the authorities. Yes, the title sounds like a soap opera (It's actually from Shakespeare, specifically Macbeth), but this is a particularly strong Star Trek episode through and through. 

"The Enterprise Incident"

Justin Lin, who directed this summer's Star Trek Beyond, picks this tale of intrigue as his favorite. 

"A good old-fashioned spy thriller set in the Neutral Zone. What’s not to love?" Lin asks. "We get to see my favorite version of Kirk: the tactician. His ruse is brilliant and daring, but it’s Spock who steals the show in his interaction with the female Romulan commander. We see him in rare form, opening up his human and—dare I say—sexual side. Of course, Kirk’s ploy succeeds and the cloaking device is stolen, but Spock derides the fleeting nature of such military victories and says to the female commander something emblematic of everything great about Star Trek: 'I hope that you and I have exchanged something more permanent.' "

The episode was loosely inspired by a real-life incident where the USS Pueblo was attacked by North Korean forces after being accused of sailing into its territory in January 1968.

"The Menagerie"

Mr. Spock commits mutiny on the Enterprise in order to get Christopher Pike, his former commander, back to the forbiden planet Talos IV.  We eventually learn that years earlier, Pike and Spock visited the planet, where Pike was horribly mutated — and Spock is trying to get his former commander there to be healed. 

"It is a story of Spock’s loyalty to his former commander as well as to Captain Kirk and of Spock’s bravery as he risks his own career and reputation," recalls Adam Nimoy, son of Leonard Nimoy ad director of For The Love of Spock, which hits theaters Sept. 9. "Although he refuses to admit to it, Spock sets aside logic to do the right thing, and I just loved it."

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"Amok Time"

For fans who'd spent the show's first year swooning over Leonard Nimoy's pointy-eared alter-ego, second season opener "Amok Time" was everything they could've hoped for and more: Not only did they get to go back to Spock's home planet, they also got to see two things they'd dreamt of but never expected: Spock in the throes of passion — apparently, Vulcans are very like dogs in heat every seven years — and Spock fighting Kirk to the death … or, at least, that's what it seemed like at the time. Written by noted sci-fi author Theodore Sturgeon, this episode showed that Trek's second year would be, if anything, even bolder than its first.

"The Devil In The Dark"

"The Horta has a funny story," says original series story editor D.C. Fontana of the episode's alien. "Stuntman, actor, creature creator Janos Prohaska did creature work for us. [Writer] Gene Coon, Gene Roddenberry and I were in the office and Janos came in and said, 'Come outside, I want to show you guys something.' So we went outside, and here's this a lump of what looked like foamy bubbles. He said, 'Just watch,' and laid a rubber chicken out on the street, and crawls into this rubber bubble suit and crawls towards the rubber chicken and the chicken disappears and a trail of bones comes out the back. Roddenberry, Coon and I were laughing our heads off, and Gene Coon said, 'I've got to do something with that.' "

That something turned out to be the Horta, an alien threat who isn't so sinister after all. 

"You think it's a monster killing the miners, and you find out it's a mother protecting its young!" says Fontana. "That was the first time we did the Vulcan mind meld, and that turned out well, but we also found that this alien isn't what you think it is. There's a human aspect that we can understand and begin to work with this thing."

"The Naked Time"

[youtube https://www.youtube.com/watch?v=M58aP5DtNqY]

A swashbuckling (and shirtless) Sulu is perhaps the single most enduring image from the original series, with the officer infected with a virus provoking him to act out his inner most desires. George Takei had just three weeks of "frantic fencing lessons" to prepare for his scenes, he recalled in his 1994 autobiography, To The Stars. Days before shooting, director Marc Daniels dropped another surprise: he would be performing the scenes shirtless. "Straightaway, I got down horizontally on the floor, put my feet on the couch, and began pumping out push-ups to build up a photogenic chest," Takei recalled in his book.

"Where No Man Has Gone Before"

[youtube https://www.youtube.com/watch?v=QT4fm0f2lZY]

After the first Star Trek pilot failed to catch fire, Roddenberry enlisted Gary Lockwood, who was about to shoot 2001: A Space Odyssey and had worked with the Star Trek creator on The Lieutenant. Trek producers believed Lockwood's involvement could help seal the deal — and they also brought on a new captain (Kirk) as well as Mr. Scott and Sulu. In the story, Kirk must grapple with the value of human life after an old friend and shipmate Gary Mitchell (Lockwood) gains dangerous (and growing) power from the edge of the galaxy. 

"The pilot sells, and 20 years later Roddenberry said to me that Gary Mitchell was the character that got Star Trek on television," says Lockwood. 

"Arena"

[youtube https://www.youtube.com/watch?v=4SK0cUNMnMM]

On the surface, it's an episode about Kirk fighting a giant lizard man, but it's about so much more. Namely: humanity, ingenuity and ultimately, mercy. After being forced to fight to the death, Kirk spares the life of the Gorn. Those impressive Gorn sounds were courtesy of Ted Cassidy, best known as Lurch on another '60s classic, The Addams Family. The image of Kirk fighting the Gorn is so indelible that even if you don't know the alien's species, you know his green skin.

"The Trouble With Tribbles"

[youtube https://www.youtube.com/watch?v=B2T1QX7BEyg]

Writer David Gerrold credits his interest in ecology with the origins of this classic episode. "I'd heard about rabbits getting out of control in Australia," he remembers, " and I thought, this is a very weird, very funny effect of introducing an invasive species into an environment without an appropriate predator. So, I was thinking for Star Trek, not all the aliens we meet are going to be scary or ugly — some of them are going to be cute and friendly and we're not going to recognize what kind of danger they are until it's too late." The teleplay was Gerrold's first professional credit, and he worked hard to make it the best that he could. "I had studied the Star Trek structure very carefully and put every scene on a 3 by 5 card until each scene demanded that the next scene followed," he says. "As funny as the script turned out, I was proudest of the structure of the episode. You could take all the jokes out, and it would still work as an adventure."

"Let That Be Your Last Battlefield"

[youtube https://www.youtube.com/watch?v=STQNi7ArRl8]

It's understandably challenging for William Shatner to pin down a favorite episode among all the greats, but when pressed, he chooses this one. The hour sees guest star Frank Gorshin play an alien, whose face is half black and half white and who hates those of his species with the colors reversed. 

"That beautiful concept, without shaking a finger, illustrated the ridiculousness of race hatred, and it was very entertaining as well. The magnificence of the idea is obvious," says Shatner. The actor says part of the brilliance of Trek is its ability to entertain without preaching.

"We use to say, 'You send a message by telegram. Make [your show] entertaining," says Shatner. "But when you can combine both, like that idea, it becomes both dramatic and obvious. And you become aware. Those were the best of the Star Trek episodes."

"Mirror, Mirror"

[youtube https://www.youtube.com/watch?v=_oOqQ38XLv8]If Star Trek gave anything to the world, it's the idea that evil versions of characters have goatees, an idea ironically put forward by the Spock of the Mirror Universe — who isn't actually evil, per se. That's a good thing, because if he had been, it's possible that Kirk, Bones, Scotty and Uhura might have been trapped in the morally-flipped alternate timeline for good, having to deal with the stomach-bearing outfits for women, the workplace harassment nightmare that is the Agonizer and George Takei's wonderfully over-the-top Evil Sulu for the rest of their fictional lives. A fun look at the roads not taken (including a more military-focused Starfleet), this episode would go on to inspire sequels in both Deep Space Nine and Enterprise. 

"Space Seed"

[youtube https://www.youtube.com/watch?v=B_c1Odol9xw]

No Star Trek episode has paid off quite like this one. Ricardo Montaban's single appearance on the original series as the 1990s warlord Khan Noonien Singh set the stage for the undisputed greatest Star Trek film ever, The Wrath of Khan, set 15 years after Kirk and the Enterprise stumbled upon the Botany Bay. "Space Seed" sees Kirk fight his intellectual and physical superior — and win despite the long odds. Nothing is more Kirk than that. 

"Balance of Terror"

[youtube https://www.youtube.com/watch?v=JGn948_PXTU]

The acclaimed episode was inspired by submarine warfare and introduces the Romulans, with whom the Enterprise engages in a claustrophobic game of cat and mouse. The episode tackles themes such as the futility of war and xenophobia, with Mr. Spock facing discrimination from his own crew when it is revealed that Romulans and Vulcans not only look similar, but also share a common heritage. 

"City on the Edge of Forever"

[youtube https://www.youtube.com/watch?v=KFqD7s-A6VU]

Never mind the behind-the-scenes controversy. Credited writer Harlan Ellison was heavily rewritten by Roddenberry, D.C. Fontana and others before the episode was shot, and decades later sued CBS for a share of profits from the episode. Just enjoy one of the true classic hours of science fiction TV as a dazed and confused McCoy travels back in time and accidentally rewrites history, forcing Kirk and Spock to follow and learn firsthand how hard it is to do the right thing for the greater good.

"I knew this episode was going to be special, not because I’m prescient, but because a couple of months earlier, I had interviewed series creator Gene Roddenberry for the Daily Sundial, the campus newspaper at San Fernando Valley State College," recalls journalist Fred Bronson, who would go on to form a friendship Roddenberry. "Aside from telling me that the purpose of television was to sell toothpaste, Roddenberry talked about an episode that had been recently filmed that he said was good enough to be a motion picture — and long enough as well, as they had to delete a lot of footage in order to make it fit the hour-long slot."

For fans of unexpected celebrity appearances, the love interest in this episode? None other than Joan Collins

"The best episodes of Star Trek (or any series) were always the ones where you absolutely believed everything that was happening was real and that you were not being manipulated by the writer," says Bronson. " 'The City on the Edge of Forever' felt authentic from the opening scene on the bridge of the Enterprise to the heartbreaking ending, when Capt. Kirk must allow the love of his life, social worker Edith Keeler, to die in a traffic accident. For years, I couldn’t watch reruns of that final scene without bursting into tears. From Spock’s declaration that trying to create a mnemonic circuit in the America of the 1930s was working with 'equipment…hardly very far ahead of stone knives and bear claws' to Kirk’s explanation to a police officer that Spock’s ears were the result of a childhood accident involving a 'mechanical rice-picker,' the dialogue of this classic episode is etched in my brain as the story that will live forever as Star Trek’s finest hour."

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