Essential Star Trek: Watch TOS in One Weekend

Last updated on April 3, 2022

Recent Star Trek series like Star Trek:Discovery has some people wanting to go back and watch Star Trek: The Original Series (TOS), The Next Generation (TNG), and the other series. But who has time for that? I mean, I LOVE Trek, but there is A LOT of Trek to watch… And if we’re talking TOS, there’s actually only 79 episodes over 3 seasons (I know, these days, a new season of a show is like 10 episodes… but back in the day, it was normal for a season to be 22-23 episodes of a show).

With TOS, each episode was about 50 minutes. That’s nearly 66 hours’ worth of content or two and a half days uninterrupted. But well, you need to sleep… and might have a job… so let’s say you’re only watching four hours a day. That’ll take you still more than two weeks.

“But Adeena… I don’t have two weeks! I just have this one weekend!”

Ok – let’s assume you have four, maybe six, hours on Friday (because you worked, and you’re going to come home with some good take-out or delivery and going to settle in until you need sleep). Then let’s assume you can spend 8 hours each on Saturday and Sunday for a grand total of 20-22 hours. That’s about a third of the entire series.

That’s good, because you probably don’t need to watch ALL of it, anyway. I mean, you do. And if you have the time, I would recommend watching all of it. But if 20-something hours are all you can spare, keep reading because…

… given you only have this one weekend, below is my list of essential TOS.

What makes them essential? I put episodes on this list that help set the stage for later Trek and show you were some elements (and even pop culture) come from. There are several “firsts” on this list… like the first time we see the Romulans. (Although not all “firsts” are represented. For example, I left off the first time we see the Klingons, which is the episode “Errand of Mercy.”)

Yes, watch them in order! They were not all filmed in this order, which is interesting, but I firmly believe when anyone asks: what order should I watch anything regarding any fandom, it should always be in the order it was available to the public. (I’ll likely expand on that concept another day).

I include a few notes on the episodes below. Note that I do not mean this list to be a “top” episodes of all time. This is an “want-to-understand-what-all-the-hoopla-is-about” list. There are plenty of other “top 10” episode lists… and actually, many of the episodes below will be on most, if not all of those lists.

Without further ado… here are all the must watch episodes of TOS:

Season 1 (S1)

1. “Where No Man Has Gone Before” (Original air date: 22 Sept 1966)
   • This is the second pilot, the episode that got ST on the air. For that reason, I find some historical significance to watching it. It’s the episode that sold the series.
2. “The Naked Time” (Original air date: 29 Sept 1966)
   • This is a great episode, and one that has a direct sequel in TNG. George Takei also spends an entire chapter talking about it in his autobiography.
3. “The Menagerie” Parts I and II (Original air dates: 17 Nov and 24 Nov 1966)
   • These are OPTIONAL… if you have an extra almost 2 hrs above the 23 or so… These were pieced together from the original pilot, “The Cage.” They’re cool because you see Captain Pike, the captain of the Enterprise before Kirk, and Spock’s prior captain. And, there is now a little tie in with Star Trek Discovery. But if you’re short on time, I would skip these now…. only because these are the ones you could watch out of order. Come back later.
4. “Balance of Terror” (Original air date: 15 Dec 1966)
   • This is the first time we see the Romulans. That’s enough justification for this episode.
5. “Shore Leave” (Original air date: 29 Dec 1966)
   • This one you’ll rarely find on other people’s lists, but it was always one of my favorites. I think it’s not only because McCoy has a bit of a love interest, but you do get to learn a bit more about the backgrounds of some of the characters. Plus, it’s fun. Who doesn’t like to relax on shore leave?
6. “Arena” (Original air date: 19 Jan 1967)
   • I have this here because of the iconic scene with Kirk fighting the Gorn. Many people consider this to be one of the best episodes of the series. I am not one of those people, but I will admit that there are a lot of interesting aspects when you consider what happens when we start exploring the unknown!
7. “Tomorrow is Yesterday” (Original air date: 26 Jan 1967)
   • The first, but not the last, time the Enterprise time travels. I love the time travel episodes. It’s also the first episode written by D.C. Fontana.
8. “Space Seed” (Original air date: 16 Feb 1967)
   • Kaaaaahhhhhhhnnnn!!!! Need I say more? You need to see the first episode with Kahn. Plus, it has my favorite McCoy moment of all time — when Kahn has a knife to his throat and he doesn’t flinch!
9. “A Taste of Armageddon” (Original air date: 23 Feb 1967)
   • An interesting and unusual take on war and computer automation. I don’t want to give anything else away.
10. “The Devil in the Dark” (Original air date: 9 Mar 1967)
    • It’s the first time McCoy says, “I’m a doctor, not a…” (And this is now the third time I’ve referenced McCoy. Just in case you needed any hints who my fave TOS character is.) But that’s not the reason to watch it. It’s the first time our crew deals with a unique type of life form, and I believe it’s the first time Spock does a mind meld.
11. “The City of the Edge of Forever” (Original air date: 6 Apr 1967)
    • Written by Harlan Ellison, starring Joan Collins… it had all the makings of a fantastic episode and didn’t disappoint. Watch this because it is frequently seen as one of the best episodes. Watch this because everyone gave fantastic performances — and the tragic ending was very atypical. Watch this because we will see The Guardian again.
12. “Operation — Annihilate!” (Original air date: 13 Apr 1967)
    • The last episode of Season 1. It’s a great Spock episode and we get more tidbits about the Vulcan’s. We get more tidbits about Kirk’s family. And they shot much of this at the old TRW, which is now part of Northrop Grumman (the company I work for… and so many of my fellow engineers are gaga over the fact that a Star Trek episode was shot at our location)!

Season 2 (S2)

13. “Amok Time” (Original air date: 15 Sept 1967)
    • I’m a big fan of the episodes where we learn a lot about the culture of one of the other key species of the series. In this case, that’s Vulcan. This is also where we begin to see how secretive Spock is about his personal life. When ST Discovery came out, a lot of people be like: how could we not know Spock had a sister? Enter T’Pring. (Watch and you’ll see who she was… and then for more secrets, see episodes like “Journey to Babel” which is also on this list, and the movie Star Trek V: The Final Frontier. Spock was SECRETIVE about his personal life!)
14. “The Changeling” (Original air date: 29 Sept 1967)
    • Subtitled: Keep these instructions for later for when an AI thinks it’s better than you.
15. “Mirror, Mirror” (Original air date: 6 Oct 1967)
    • The Mirror Universe started here. Great episode and see where that sub-arc all began.
16. “The Doomsday Machine” (Original air date: (20 Oct 1967)
    • This one I felt pressured to include because many people would be upset if I didn’t. A Moby Dick theme often recurs in Star Trek, and it starts here. It is an enjoyable episode — the drama and tension is solid all the way through.
17. “I, Mudd” (Original air date: 3 Nov 1967)
    • This episode is fun. Plus, you need to know who Harry Mudd is before you see Rainn Wilson reprise the character in Discovery. There were actually two episodes with Mudd in them. The first was “Mudd’s Women” in Season 1. I didn’t include that one on the list only because I couldn’t include all of them. And the only thing you need to know going into this one is that Mudd is a conman.
18. “Journey to Babel” (Original air date: 17 Nov 1967)
    • What!? Spock continues to be secretive about his personal life? Yup. In this episode we meet Spock’s parents for the first time, but no one knows it until they’re standing right there… Kirk to Spock: “Wanna go see your parents?” Spock to Kirk: “Uh… about that…. this Vulcan and his human wife standing right here? They are my parents.” (I paraphrased that.) This is a must-see episode.
19. “The Deadly Years” (Original air date: 8 Dec 1967)
    • I’m probably the only person who is going to include this episode on a list like this. But I have good reasons: 1) Chekov has a decent role to play 2) While the episode has been criticized for its stereotypical and non-helpful view of aging, I think they did a good job and it was Shatner and Kelley play older versions of themselves was interesting 3) We get a little more insight into Starfleet Command and 4) Romulans. I like every tidbit of Romulan stuff in TOS and think that’s worthwhile to watch.
20. “The Trouble with Tribbles” (Original air date: 29 Dec 1967)
    • Tribbles. Need I say more? Okay, a little more. Tribbles are iconic Trek and this is the first episode they appear in. Besides, you’ll appreciate the DS9 episode, “Trials and Tribbleations” that much more if you’ve seen the original episode once or twice or a couple dozen times.
21. “A Piece of the Action” (Original air date: 12 Jan 1968)
    • TOS did several episodes that were parallel Earth or parallel Earth-like. I attribute a lot of that to considerations for ease of production — I don’t believe that anyone believed or believes that when we eventually go out exploring the galaxy, we’re going to find parallel Earth’s to the level of parallelism shown in TOS. Nevertheless, this was a really fun and funny episode, establishing the fact that Trek can incorporate some comedy as well. And after you watch, if you ever want to play a game of Fizzbin, let me know! I’m really good!
22. “Bread and Circuses” (Original air date: 15 Mar 1968)
    • This is another “parallel Earth” episode and the one I think I enjoyed the most possibly it was of the extreme nature of the alternate history portrayed. It showcases Kirk, Spock, and McCoy as the iconic trio and even talks handles the Prime Directive a bit. This is as classic a TOS classic as it gets.
23. “Assignment: Earth” (Original air date: 29 Mar 1968)
    • Another time-travelling episode (I like those a lot for some reason).

Season 3 (S3)

25. “The Enterprise Incident” (Original air date: 29 Sept 1968)
    • Season 3 was… um… not as good as the other two. Hence why this list is so imbalanced and there are only a small handful of episodes I recommend. But this one is an absolute must to continue to understand the Romulans. And Starfleet.
26. “Elaan of Troyius” (Original air date: 20 Dec 1968)
    • Several episodes on this list are here so you understand a reference later. In this case, Scotty mentions Elaan of Troyius in the TNG episode, “Relics.” But it was also a neat episode filled with interesting tidbits and we see what makes Kirk, Kirk.
27. “Let That Be Your Last Battlefield” (Original air date: 10 Jan 1968)
    • Another iconic episode with a recognizable alien species. I actually don’t think this was a great episode (in terms of writing, etc), but there’s something very Trek about this episode.
28. “All Our Yesterdays” (Original air date: 14 Mar 1968)
    • Yes, this is another episode where Spock gets a love interest. And it’s another time travel episode — but a different version of time travel. It’s also another “trio” episode and I think those are worthy of watching in a weekend.
29. “Turnabout Intruder” (Original air date: 3 Jun 1969)
    • The last episode of TOS to ever air, although that was not the intent (it was supposed to air a few months earlier but was pre-empted by a special report on former President Eisenhower who had died earlier in that day). I agree with a lot of others that this was one of the worst Trek episodes. So why am I recommending watching it? Because it was the last Trek people got to see for several years. I think it’s worthy of appreciating that fact.

Agree with the list? Don’t agree? Comment below! I feel like someone, somewhere is going to mention the fact that I didn’t include these episodes: “The Enemy Within,” “The Squire of Gothos,” and “The Corbomite Maneuver.” (If you have more time than what I assumed, yeah, those should get added to the list as well!)

If this wasn’t enough Trek for you, and you have the time and can watch the entire series, see the full list here: https://en.wikipedia.org/wiki/List_of_Star_Trek:_The_Original_Series_episodes

Finished with TOS? Move on to The Essential TNG and the other series!