10 Most Important Episodes Of Star Trek: The Original Series
7. Amok Time (2.1)
The second season premiere of Star Trek, Amok Time, was not only the very first episode to take place on Spock's home world of Vulcan, but would also prove to be the only episode of TOS to do so.
Not to say that Vulcan isn't significant. On the contrary, the planet and its people are incredibly important Star Trek lore and this episode was the very first to establish many of the various customs, beliefs, and traditions held by the native Vulcans. These elements would endure throughout the years, becoming integral to future Star Trek stories, including the stellar film Star Trek: First Contact, where we see humans encountering the Vulcans for the first time.
This episode's value to the franchise is twofold. Not only did it lay the groundwork for Vulcan-based Star Trek Lore, but it is also crucial in regards to its portrayal of how strong the brotherly bond between Captain Kirk and Mr. Spock is.
It is so powerful that when Spock thought he had killed Kirk, his Vulcan nature went out the window, as all that mattered was the compassion he felt for his best friend. Also, this would ultimately come full circle in Star Trek II: The Wrath of Khan, when Spock gave his life to save the Enterprise while expressing his undying friendship to Kirk.
It is undoubtedly one of the most enduring and time-tested relationships not only in Star Trek, but science fiction as a whole and this episode represents its unshakable foundation.