Top 10 Star Trek Episodes of All-Time

45 years ago today, Star Trek premiered on NBC. Seventy-nine episodes, an animated series, eleven movies, and four spin-off series later; the little show that NBC cancelled after three seasons has become a cornerstone of science fiction. What better occasion to list the ten best episodes of the Original Series?

All of these episodes are available for online streaming on StarTrek.com.

1. The City on the Edge of Forever

I doubt anyone would disagree that this is the best episode of the Original Series, and possibly of all Trek. This is the one where McCoy, while tripping out on drugs, runs through the Guardian of Forever and prevents Joan Collins from being killed, which prevents America from entering WWII due to her pacifist activism. So Kirk has to go back in time, fall in love with her, and then watch her get hit by a truck. Watch this episode on the official site.

2. Mirror, Mirror

Spock has a goatee! Admit it, when you saw that for the first time; you thought it was the coolest thing ever. Kirk gets tossed into an alternate universe where the Federation is a warlike empire and manages to get to the Spock of that universe, who we later learn in DS9 was able to change things. Watch this episode on the official site.

3. Space Seed

 Khaaaaaaaaaaaan! This little episode, where the Enterprise finds genetically engineered supermen frozen in stasis would lead to the best Star Trek movie ever made. If you haven’t seen it, watch this episode on the official site.

4. The Trouble With Tribbles

This is perhaps one of the most famous of all Original Series episodes. It’s lighthearted, and a lot of fun. They even chose this episode to revisit when on Deep Space Nine they wanted to include that crew in an Original Series episode. Watch this episode on the official site.

5. Balance of Terror

Romulans look just like Vulcans? Your brain explodes! One of the best episodes of the Original Series introduced the Romulans, who would become a major race in the franchise, as well as giving some future-history when the Earth-Romulan war is talked about. Had Enterprise continued, we would’ve seen that war. Watch this episode on the official site.

6. The Doomsday Machine

How does Kirk destroy an indestructible planet killer? By flying a starship inside it and blowing it up! Watch this episode on the official site.

7. Amok Time

Spock has to return to Vulcan because he’s horny, and while there he and Kirk fight to the death. Complete with That Fight Music. One of the more famous episodes of the original Trek, if only for That Fight Music. Watch this episode on the official site.

8. Arena

The episode that forever put California’s Vasquez Rocks on the map. They used that filming location numerous times over the history of Star Trek, but it is 'Arena' that made it famous. Kirk’s ingenuity is on display in this episode when he makes a bazooka out of almost nothing to kill the Gorn. Watch this episode on the official site.

9. Devil in the Dark

This is Shatner’s favorite Star Trek episode, and for good reason. Nothing really funny to say about this episode, as it’s pretty much a perfect example of what Star Trek can and should be. Watch this episode on the official site.

10. Journey to Babel  

Journey to Babel is like a murder mystery on the Enterprise, with Vulcans, Andorians, and Tellerites all in on the fun and an Orion tossed in for some flavor. The episode introduced Spock’s parents, who would become major recurring characters in Trek. Watch this episode on the official site.