10 Best Star Trek The Original Series Episodes

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It’s been 50 years this summer since Star Trek debuted. It’s hard to imagine today that the show tanked in the ratings and was canceled after three seasons; it’s even harder to believe how that failed series has evolved into a blockbuster franchise, spawning so many spin-off TV series and movies that the seminal 1960s show has been rebranded as Star Trek: The Original Series. Some of those episodes seem very dated today, but many have held up surprisingly well and seem as fresh and culturally relevant now as when they first aired. From a longtime Star Trek fan, here’s my take on the 10 best episodes. It’s impossible to avoid all spoilers in a story like this, but I’ve tried not to give away the greatest scenes and plot twists.


10. Where No Man Has Gone Before (Season 1, Episode 3)

Gary Lockwood and Sally Kellerman guest starred in the second pilot for Star Trek, Where No Man Has Gone Before. © CBS Corp.

Two of the three national networks in the mid-1960s originally rejected Star Trek. CBS refused to even consider the concept, while NBC commissioned a pilot, then rejected it. But Lucille Ball, president of Desilu Productions, persuaded NBC to order a second pilot. The result, Where No Man Has Gone Before, persuaded network execs to order the series. It certainly didn’t hurt that the pilot featured two attractive guest stars as crewmembers: Sally Kellerman (best known for her role as Maj. Margaret “Hot Lips” Houlihan in the 1970 film M*A*S*H) and Gary Lockwood (who starred in the classic 2001: A Space Odyssey). After the Enterprise travels through the supercharged edge of the galaxy, both helmsman Gary Mitchell and Dr. Elizabeth Dehner develop psychic, almost god-like powers, posing a threat to the ship.


9. By Any Other Name (Season 2, Episode 22)

In a familiar Star Trek plot theme, one of the red-shirted crew members is about to die. © CBS Corp.

One of the most common plot lines in Star Trek involves aliens seizing control of the Enterprise. One alien race, the Kelvans, carried an interesting weapon, which could reduce Enterprise crewmembers into small chalk-like blocks. Crush the block, the person dies. After the Kelvans take the Enterprise and modify it for a 300-year flight back to the Andromeda Galaxy, they reduce most of the crew into the little blocks. Most fans seem to prefer another aliens-take-the-Enterprise episode, Wink of an Eye, but the situation really does seem hopeless in this episode.


8. Assignment: Earth (Season 2, Episode 26)

Teri Garr and Robert Lansing would have starred in a Star Trek spin-off series based on the Assignment: Earth episode. © CBS Corp.

The Enterprise travels back in time to 1968, and Kirk and Spock try to stop a mysterious alien from interfering with a U.S. rocket launch. Things go wrong and World War III almost breaks out. Star Trek producer Gene Roddenberry used the episode, with guest stars Robert Lansing and Teri Garr, as the pilot for a spin-off TV series, Assignment: Earth, but found no takers.


7. Space Seed (Season 1, Episode 22)

Ricardo Montalban steals the show in Space Seed. © CBS Corp.

With apologies to Fantasy Island fans, this is the role Ricardo Montalban was born to play. The Mexican actor plays Khan, a genetically engineered superhuman who has been in suspended animation since the 1990s. After Kirk & Co. encounter Khan and dozens of his fellow superhumans aboard an ancient spacecraft, Khan awakens and announces his plans to conquer humanity. His first target: the Enterprise.


6. Balance of Terror (Season 1, Episode 14)

Mark Lenard played three different characters in the Star Trek franchise. © CBS Corp.

The Enterprise encounters Romulans for the first time. The Romulan vessel has a cloaking device, and Kirk and the Romulan commander (played by Mark Lenard) match wits in an episode that plays out like The Hunt For Red October in space. “You and I are one of a kind,” the admiring Romulan leader says to Kirk. “In a different reality, I could have called you my friend.” Lenard would go on to play two other different characters in the Star Trek franchise.


5. The Doomsday Machine (Season 2, Episode 6)

The Doomsday machine posed a threat to the Enterprise. © CBS Corp.

William Windom steals the show here as Commodore Matt Decker, who is obsessed with extracting revenge on a giant planet-killing machine that killed his entire starship crew. When Decker seizes control of the Enterprise, it puts the ship in mortal danger.


4. The Naked Time (Season 1, Episode 4)

Sulu goes berserk with a sword in The Naked Time. © CBS Corp.

After the Enterprise landing party brings back a strange virus from a doomed research station, the illness spreads throughout the crew, resulting in irrational behavior. As the starship hurtles out of control toward the planet below, we’re treated to the unforgettable image of a shirtless Lt. Sulu brandishing a sword like one of the Three Musketeers. George Takei devoted an entire chapter in his autobiography explaining why this is his favorite episode.


3. The Trouble With Tribbles (Season 2, Episode 15)

Capt. Kirk has his hands full with tribbles in this classic episode. © CBS Corp.

It would have been easy for Star Trek to take itself too seriously, filled with danger and ominous situations. But the series displayed a wicked sense of humor, usually shown in the interplay between the main characters. The Trouble With Tribbles introduces an outside element, fluffy, purring little tribbles, to ratchet up the comedy. This is a brilliantly funny episode.


2. Mirror, Mirror (Season 2, Episode 4)

Spock rocks a Van Dyke in the episode Mirror, Mirror. © CBS Corp.

Kirk, McCoy, Scotty and Uhura are transported to a parallel universe, where an Enterprise featuring a bearded Spock is part of an evil empire. Meanwhile, their counterparts from that universe are inadvertently beamed aboard the regular Enterprise. Aboard the evil starship, assassinations are standard procedure, and Sulu, Chekov and Spock all take aim at Kirk. The premise seemed like crazy science fiction at the time, but many leading cosmologists, including Stephen Hawking and Neil deGrasse Tyson, now believe we are part of a multiverse, with infinite parallel universes. Perhaps somewhere out there is a universe where the original Star Trek had a successful 12-season run on NBC.


1. The City on the Edge of Forever (Season 1, Episode 28)

The Enterprise crew discovers the perils of time travel in The City on the Edge of Forever. © CBS Corp.

There are so many great elements to this episode, including the fine performance by guest star Joan Collins, and her character’s romance with Kirk. But it’s also surreal seeing Kirk, Spock and McCoy travel back in time to the Great Depression. Then there is the classic time-travel dilemma of a timeline disruption that leads to a vastly different future … one where Nazi Germany won World War II. Kirk and Spock prevail in righting history, but at a tragic cost. That prompts Kirk to remark at the end of the episode, “Let’s get the hell out of here,” one of the first uses of profanity in prime-time TV.


One More: Day of the Dove (Season 3, Episode 7)

Klingons and Enterprise crew members fight for control of the ship in Day of the Dove. © CBS Corp.

This doesn’t make the top 10 here, but it’s definitely a top 20 choice for me, which puts it about 30 spots higher than many rankings that completely diss this show. There’s a lot to like here. An alien energy force feeds on violence, and becomes ever stronger as the Enterprise crew fights Klingons aboard the ship. Meanwhile, the Enterprise speeds at warp 9 toward the edge of the galaxy, as both Klingons and crewmen fight for control of the ship. Not sure why this episode ranks so poorly with so many fans.


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The author is a longtime professional journalist who has interviewed everyone from presidential contenders to hall of fame athletes to rock 'n' roll legends while covering politics, sports, and other topics for both local and national publications and websites. His latest passions are history, geography and travel. He's traveled extensively around the United States seeking out the hidden wonders of the country.