[John's Note: friend and blog reader Ampersand returns with a great contribution, below.]
Hey, John. Ampersand here. Been a while since I've contributed, but I couldn't resist a Star Trek challenge!
But before I present my picks, I'd like to comment: I recently re-watched all 79 episodes of The Original Series, in production order, and what struck me was that the first 20 or so episodes ranged from excellent to pretty good. (The first real turkey was "The Alternative Factor.")
That's, like, 15 hours of great space opera! And in that genre, what had come before? Forbidden Planet, of course, and maybe a couple episodes of Twilight Zone and Outer Limits, but I can't think of anything else. It made me really appreciate what Roddenberry and his team had accomplished way back when I was but a lad.
Anyway, here's my picks:
20) "Whom Gods Destroy:" An Andorian, a Tellarite, and an Orion slave girl walk into a bar ... Not a great episode, but builds on continuity and features one of the great Trek villains. Bonus: Gets referenced in "Buffy" years later. Also: Yvonne Craig!
19) "I, Mudd:" Kind of dumb, but pure comedy if you know and love the characters. Shut up, Stella!
18) "Assignment: Earth": What could have been... Kirk & co. don't actually get much to do in this backdoor pilot, but hey, Terri Garr! Also a very cute cat.
17) "A Piece of the Action:" Another comedy episode with a cute concept, kinda stupid but fun. Right, Spocko? Check.
16) "Requiem for Methuselah:" Okay, really just a sci-fi soap opera, but maybe I'm just a sucker for "secret history" stories.
15) "The Squire of Gothos:" Trelane's a baby Q, right? Whatever, it sets the template, and it's fun.
14) "Day of the Dove:" Not necessarily the first time the Klingons were treated like equals, but maybe the first time they were truly sympathetic. Yet another variation on the classic Trek theme: Those who you think of as enemies may well turn out to be your allies.
13) "Mirror, Mirror:" High concept, great execution. Now everyone's evil twin has to have a goatee.
12) "The Menagerie (I & II --yes, I'm cheating):" Clever re-use of existing footage, but so much more; the Enterprise had a Captain before Kirk, there's a history here, and Trek mythology begins ...
11) "The Doomsday Machine:" Damn good story with a damn good guest star, 'nuff said.
10) "Tomorrow is Yesterday:" Sure, the time travel mechanics are a bit muddy, but the dual fish-out-of-water scenarios (Capt. Christopher on the Enterprise, Capt. Kirk on "present-day" Earth) are great. Funny, thrilling, and a more than a little bit touching.
9) "Journey to Babel:" One of only two (!) TOS episodes to feature a Vulcan other than Spock*, this fine ep not only introduces us to Spock's parents, but fills us in a bit on the politics of the UFP. And, it's a great story.
.... *Pedantic footnote: "Surak" appears in the (pretty terrible) Robo-Abraham Lincoln episode, but he's a simulation, not a Vulcan.
8) "Amok Time:" The other TOS ep that has Vulcans, but more importantly, a terrific exploration of the relationship between Kirk and Spock (and, to a slightly lesser extent, McCoy).
7) "The Devil in the Dark:" Another really great "Your enemy isn't really your enemy" episode.
6) "Balance of Terror:" One of the outstanding space battle episodes, but with a bold statement about prejudice included. Bold for the time, sadly still relevant now.
5)"Arena" The one that made James T. Kirk my hero. He had a chance to kill the Gorn, but he didn't because that's not what heroes do. Classic.
4): "The Enemy Within:" Hey, have I mentioned the classic TOS trope, "Your worst enemy is actually your best friend"? This has got to be the ultimate expression of that. Too bad the dog has to die, though.
3) "The Trouble with Tribbles:" Just pure joy from start to finish. Funny, yes, but with a good story behind it. And annoyed-but-amused-in-spite-of-himself Kirk is one of the best Kirks.
2) "The Corbomite Maneuver:" "Not chess, Mr. Spock. Poker!" Our introduction to Kirk the trickster. Some call this the "real" TOS pilot, and I can't really disagree.
1) "Spock's Brain:" An elegant exploration of the philosophical ramifications of ... no, just kidding.
Not Kidding :
1) "The City on the Edge of Forever:" This one's got it all: action, humour and a romance for the ages. In fact, in my biased opinion I would say that this episode on its own is one of the best sci-fi films of the 60's, and maybe all time.
Thanks for listening!