18. Patterns Of Force
While Nazi Germany and World War II were still fairly fresh on peoples minds in 1968, this episodes relevance remains and I believe this is the most underrated episode in the show's 79 episode run. In one of the first (if not the very first) episodes to deal head-on with the Prime Directive of non-interference with other cultures, John Gill, A Starfleet Academy professor and friend of Captain Kirks, goes missing on the planet Ekos, and Kirk and Spock beam down to find a planet wide recreation of Nazi Germany, the Fuhrer being none other than John Gill. The Ekosians form the Nazi movement to eradicate the neighboring Zeons from their planet. After going undercover as S.S. guards, Kirk and Spock find Gill drugged and barely coherent, his words to the people being fed to him through Deputy Fuhrer Melakon. Before he is gunned down by Melakon, Gill tells Kirk that the world was in a state of total anarchy and war, and he felt that Nazi Germany was an appropriate association for the given circumstances of Ekos and Zeon. With that, the episode poses an interesting question: is a totalitarian government better than no government at all?
17. The Ultimate Computer
The Enterprise crew is evacuated to a space station holding cell save twenty or so members including the senior staff. Upon their arrival at the station, Captain Kirk is informed that they will be participating in war games with the M5 multitronic computer, invented by Dr. Richard Daystrom, founder of the Daystrom Institute mentioned throughout the franchise. Kirk is skeptical of the entire idea, especially when Daystrom mentions that M1, M2, M3 and (you guessed it) M4 were dismal failures for whatever reason. Tensions rise even more when the M5 starts playing with the power and labels the Captain as non-essential personnel. Tensions reach a breaking point, of course, when the M5 sadistically murders a redshirt, the entire crew of the U.S.S. Excalibur, and opens fire on three other Federation heavy cruisers. Daystroms fifth dismal failure causes him to go insane and be confined to a mental institution. And they all lived happily ever after.