5 Best Star Trek: The Original Series Episodes, Ranked by How Well They’ve Aged in 2026

While Star Trek: The Original Series is 60 years old, there are many stories in the show that feel relevant even today. Gene Roddenberry created a world where world politics and sci-fi intertwined, and fortunately or unfortunately, a lot of the issues predicted or explored in these episodes are still relevant to today’s society.

From philosophical thought experiments to AI integration and commentary, Star Trek has spoken about issues that we are facing now. The following five episodes represent the best of the show, ranked according to increased relevancy. These contain no dated allegories or clumsy metaphors. Here are the 5 best TOS episodes, ranked by how well they have aged.

5 The City on the Edge of Forever

William Shatner in Star Trek: TOS | Credits: Paramount

The first season of Star Trek: TOS did a lot of heavy lifting when it came to proving why such a big show needed to be on air. It was the penultimate episode of the freshman season, ‘The City on the Edge of Forever,’ that made fans feel like this was a show that was not afraid to take bold risks in storytelling. It is one of the best time-travel episodes in the franchise.

The episode sees Captain Kirk and Spock travel back in time, and the former falls in love with a social worker named Edith Keeler. However, it is revealed that her death changes the course of history, and without it, there would be no Federation or Starfleet. The reason why it feels relevant is not because of any particular tech or theme, but the fact that it could be set in any era and still hit emotionally. That is also why it ranks last.

4 The Doomsday Machine

A still from Star Trek: TOS | Credits: Paramount

When Kirk and the Enterprise follow a distress beacon, they find one of the starships, the USS Constellation, nearly destroyed, with only one survivor, Commodore Matt Decker. He reveals that the crew was destroyed by a planet-killing machine, which uses the rubble as energy. Decker suffers from mental shock and often keeps flipping out against the Enterprise crew.

Spock’s description of a self-sustaining machine that destroys without judgment reads less like a Cold War metaphor now that autonomous weapons and AI-directed strike systems move from theory to deployment. Decker’s authority over weapons despite his mental state can be seen as another commentary on human oversight.

3 A Taste of Armageddon

A still from Star Trek: TOS | Credits: Paramount

In this Star Trek episode, the Enterprise comes across two warring planets who fight only through a computer simulation. When the computer on either side marks a hit, the citizens are expected to go into a disintegration booth and die. The war thus remains endless and contained without any damage to infrastructure.

The fact that this is done to contain damage to infrastructure and not to the people is disturbing enough. It is also a commentary on the sanitized violence we see now. As people feel more desensitized to violence and do not feel it is close to home, they remain detached from it, and the violence goes on forever, as no one takes it seriously.

2 Mirror, Mirror

William Shatner in Star Trek: TOS | Credits: Paramount

Captain Kirk, Uhura, Spock, and McCoy are stranded in a parallel reality after an ion storm. In this reality, the Enterprise is serving a tyrannical fascist empire. Unlike the Federation, the Terran Empire’s underlying philosophy is conquest and assassination. Their counterparts are transported to the real Enterprise.

The episode offers a clear contrast between a pluralist society and a fascist empire. As the world becomes tighter with its regulations and wars occurring in many parts, this clear distinction is important to uphold true democratic values. Kirk’s statement to Mirror Spock about logical reasoning favoring mercy over tyranny is a value that should be applicable today.

1 The Ultimate Computer

A still from Star Trek: TOS | Credits: Paramount

This Star Trek episode is set in a test simulation, where the Enterprise is fitted with a new automated device called the M-5 unit, which takes control of ship functions. While it automates much of the work, it also does some suspicious activities, like switching off life support to certain areas of the ship. As the tests get increasingly violent, the M-5 becomes hostile towards allied ships and goes out of control.

In the age of AI, the episode rings extremely true. A technology that automates most processes but does not contain the emotional reasoning required to think during high-pressure situations is the central debate right now. ‘The Ultimate Computer’ is probably the most relevant episode for the age of AI.

Which Star Trek: TOS episode do you think is the most relevant? Comment below.

Star Trek: The Original Series is available to stream on Paramount+.