[Reader and friend Neal Patterson contributes our next Top 20 list!]
20. Spock's Brain - A guilty pleasure. More like an Irwin Allen show than Star Trek, it's still fast paced and humorous at times.
19. Amok Time - I'm probably in the minority by not putting this higher up, but other than introducing some ideas about Vulcan culture and physiology, I don't find the episode as interesting as others. Still, I felt obligated to list it since it introduces some major elements to the TOS canon.
18. Wolf in the Fold - Doesn't hold up well over time, but I still enjoy a murder mystery and it focuses on Scotty, who was my favorite character as a kid.
17. Errand of Mercy - Great commentary on the fog of war. It also introduces the Klingons and the peace treaty that plays a major role in future TOS episodes.
16. The Corbomite Maneuver - Tense storyline where the antagonist holds all the power until the very end, then we are treated to a happy ending for both sides.
15. Operation: Annihilate! - Deadly flying omelettes! I like this episode mainly because it was the episode that actually got me hooked on watching Star Trek. Plenty of action and a nice piece of backstory with Kirk's brother.
14. Metamorphosis - The real strength of Star Trek was that it could tell a tender, thoughtful story just as well as a ripping action yarn.
13. The Galileo Seven - This is probably the first serious exploration of Spock's character and the beginning of the Spock/McCoy relationship.
12. The Tholian Web - I love episodes that focus on the Enterprise crew without guest stars. This is especially good for exploring the Spock/McCoy relationship.
11. Day of the Dove - Klingons on the Enterprise! Great way to tell an exciting story on a minimal budget.
10. Journey to Babel - This episode, even more than Amok Time, lays out the most foundation for the Spock character by introducing us to his parents. Just like visiting your fiance's parents for the first time, you finally understand why someone is the way he/she is.
9. The Menagerie - Yes, I'm counting this as one episode. Great use of the first pilot to give a sense of history about Spock and the Enterprise. Both the pilot story and the new plot work well.
8. Immunity Syndrome - Another episode with no guest stars. The battle to find an answer to their dire predicament while extremely exhausted is compelling.
7. Balance of Terror - Futuristic take on the World War II submarine movies like The Enemy Below. It also has a great deal to say about prejudice and fear of the unknown.
6.The Devil in the Dark - A moving story that was so much more than the typical "monster-of-the-week" stories that populated sci-fi TV back then.
5. The Enterprise Incident - Star Trek dabbles in the spy genre. While some episodes take awhile to get going, this story is a suspenseful piece from beginning to end.
4. Space Seed - Kirk meets his Moriarty in the form of a genetically engineered superman named Khan. Not only is the episode a terrific battle of wills, it lays the groundwork for a large piece of Star Trek Universe history. Of course, it also led to what many consider the best of the Star Trek movies. Ricardo Montalban is so good in this!
3. The City on the Edge of Forever - Probably best known to fans because of Harlan Ellison's complaints about how his script was reworked, but it's still a rich narrative dealing with friendship, love, sacrifice, and loss.
2.Where No Man Has Gone Before - I like this mainly because of the strong guest cast and the quirky look of the sets and costumes. It's interesting how much the sets and costumes evolved from The Cage to this pilot to the series.
1. The Doomsday Machine - This episode is so fraught with tension from beginning to end, I can watch it over and over. William Windom is one of my favorite character actors, and he does an amazing job here of swinging through the spectrum of emotions from fear to arrogance to desperation without making it feel campy. You really suffer with him even as you are annoyed by him. Also, the interaction between Kirk, Spock, and McCoy during the climax is perfect Star Trek and feels a lot like the interplay we would see between them in the later movies. Just a perfect episode!