Star Trek: The Original Series’ Must-Watch Episodes

Star Trek: The Original Series’ Must-Watch Episodes

Star Trek. It’s one of the most quintessential pieces of science-fiction television around. And there’s a whole damn lot of it, even if you cut it down to the current eight different shows in the franchise (there’s even more on the way!). Want to start, but need a little guidance? We’ve beamed up to help you.

As part of follow our advice and help yourself to all the Star Trek, here are at least some highlights you can look forward to as you boldly go absolutely nowhere outside.

The unnamed Romulan Commander of “Balance of Terror,” the finest Star Trek ever made. (Image: CBS)

Season 1

The Cage (The Pilot)”A fascinating curiosity that has now become all the more interesting given Star Trek: Discovery‘s rejuvenation of Captain Pike, the Enterprise captain before Kirk.

Where No Man Has Gone Before (Episode 3)”This is the actual first episode of the show, the new pilot now featuring Kirk in the captain’s chair, despite the fact that it aired two episodes in.

The Naked Time (Episode 4)”A bizarre space virus essentially gets the crew…drunk? High? It’s the perfect mix of goofy and sci-fi Trek action.

The Corbomite Manoeuvre (Episode 10)”An incredible example of what could make Star Trek‘s more strategic take on space combat so fascinating, as Kirk brings the Enterprise through a tough scrape with a powerful foe.

The Menagerie, Parts 1 and 2 (Episodes 11 and 12)”This actually was an excuse to reuse a bunch of footage from “The Cage,” but it’s recontextualized in a fascinating way that adds further depth to Spock.

The Balance of Terror (Episode 14)”Quite literally the greatest episode of Star Trek ever. Kirk encounters the mysterious Romulans in a chilling, intense game of cat-and-mouse that is about so much more than just a deadly battle.

The Galileo Seven (Episode 15)”This isn’t just the origins of a great Star Trek episode concept (shuttlecraft mission goes awry), but a fascinating examination of conflict between the crew of the Enterprise and Spock’s alienness.

The Squire of Gothos (Episode 17)”You can’t recommend original Trek without at least one “So the crew basically encounters God” story. In this one at least, the god is Trelane, an extravagantly foppish and delectably camp omnipotent being.

Arena (Episode 18)”Come for Captain Kirk two-handedly thumping a space-lizard, stay for the powerful examination of the dark, primal heart of humanity when its back is against a wall.

Space Seed (Episode 22)”Meet the iconic villain of what is still the movie, as Kirk and the crew reawaken the genetically-enhanced Khan, and address a grim part of humanity’s dark history in the process.

Errand of Mercy (Episode 26)”The Federation and the Klingons go to war, and the Enterprise finds itself on the front lines with a Captain Kirk shocked by his own brutality.

The City on the Edge of Forever (Episode 27)”One of the most iconic time-travel love stories ever told, as McCoy, Spock, and Kirk find themselves thrust into 1930s New York and encounter the mysterious Edith Keeler.

Kirk has his hands full. (Image: CBS)

Season 2

Amok Time (Episode 1)”Our first visit to Vulcan explores the culture of its logic-adherent beings and proves to be a tumultuous, fascinating (and, uh, very horny) episode for Spock.

The Doomsday Machine (Episode 6)”The Enterprise goes up against a horrifying weapon of mass destruction and Federation bureaucracy in equal measure.

Mirror, Mirror (Episode 4)”See one of the genre-defining parallel universes come to life as Kirk and his officers find themselves flung to a sinister alternate universe where the Federation is a tyrannical empire.

I, Mudd (Episode 8)”If you watch one Harry Mudd episode, let it be this, a goofy romp which sees the titular rogue attempt to trap the Enterprise crew on a planet of powerful androids.

Journey to Babel (Episode 10)”Another great Spock episode, as we meet his parents (including his human mother) for the very first time.

The Trouble With Tribbles (Episode 15)”Star Trek goes full-on comedy with an incredible, hilarious romp that also happens to be about overbreeding fuzzballs and uneasy tensions between the Federation and the Klingons.

A Piece of the Action (Episode 17)”Star Trek had plenty of “planet of the weird Earth history stereotype” episodes, and they’re great fun. This one? Planet of the 1920s mobsters!

A Private Little War (Episode 19)”Kirk grapples with the ethics of intervention when he believes a low-tech planet may have acquired weaponry from the Klingons.

The Ultimate Computer (Episode 24)”Kirk faces another hyper-advanced A.I., a classic Trek trope, but with a twist: this one’s made by Starfleet itself, and will replace him as captain of the Enterprise if it outwits him!

Assignment: Earth (Episode 26)”A peculiar story that sees Kirk and Spock thrown back to the 1960s, only to discover they’re not the only unlikely beings hidden on planet Earth. What’s weird and fun is that this was actually a backdoor pilot for a potential spinoff series that never got off the ground.

“Brain and Brain, what is Brain!?” (Image: CBS)

Season 3

Spock’s Brain (Episode 1)”Look. It’s not good, per se. It’s arguably not even average. But just once in your life, you have to experience DeForest Kelley, with the utmost seriousness, turn to William Shatner and say (of Spock) “His brain is gone.”

The Enterprise Incident (Episode 2)”An intriguing examination of just how far our heroes are willing to go to outfox the Romulans, as an erratic Kirk leads the Enterprise into forbidden Romulan space.

Spectre of the Gun (Episode 6)”Here’s another of those goofy “planet of the Earth history stereotype” episodes, but this time it’s the O.K. Corral!

Day of the Dove (Episode 7)”Kirk finds himself battling his own crew as much as he does the Klingons when mysterious beings attempt to pit the Enterprise and a Klingon vessel against each other.

The Tholian Web (Episode 9)”Investigating a missing starship (that actually goes on to play a huge part in the development of the Mirror universe), Kirk and crew encounter the almighty, mysterious Tholians.

Wink of an Eye (Episode 11)”The Enterprise meets an alien species who experience time at a much slower rate, allowing themselves to be invisible to the human eye.

All Our Yesterdays (Episode 23)”The penultimate episode of the show (and so good compared to what was the actual last episode that it might as well be the final story) sees the Enterprise investigate missing colonists on a planet due for evacuation, only for Kirk, Spock, and McCoy to be thrust out of their elements.


Star Trek is available to stream, currently for free, on CBS All Access.