Some Star Trek fans look back on the original series with amusement, and admittedly, there were plenty of silly moments and special effects that didn't look quite right, but one thing the show did well was creating moments of true menace or danger, and many of these took place on the bridge of the Enterprise.
Let's take a look at a few of these moments and remember why the original series is so important to the Star Trek timeline, despite its dated appearance.
1. Kirk sets the self-destruct order in "Let That Be Your Last Battlefield" (S3E15)
When two quarreling aliens, Commissioner Bele and Lokai, find themselves aboard Enterprise, their long-standing battle causes chaos when Bele insists that Captain Kirk take them both back to their home planet, Cheron, so that Lokai can face judgment for a series of crimes. Lokai insists he's fighting for his people, who he claims have been enslaved by those like Bele, whose black-and-white face is black on the right side, which Bele believes makes his kind superior.
When the Federation denies Bele's request because they have no official treaties or involvement with Cheron, the belligerent commissioner uses his mental powers to force the Enterprise to change course toward the planet. On the bridge, Kirk tells Bele that he'll destroy the ship rather than see it under his control. He, Spock, and Scotty initiate a countdown to destruction that cannot be countermanded after the final 5 seconds. As the countdown starts, anxiety builds, and Bele agrees to Kirk's terms at the 6-second mark (Chekov especially looks like he needs to dash to his quarters for a fresh pair of uniform bottoms!)
2. Rojan deciding the bridge crew's fates in "By Any Other Name" (S2E22)
When the aliens called Kelvans take over the Enterprise in search of a new home for their people, as their galaxy is being bombarded with radiation, their leader, Rojan, decides that the crew is troublesome and therefore most will be transformed into a distilled form that resembles a porous stone. The journey back to the Kelvan Empire is a long one, and 5 Kelvans cannot keep constant watch over more than 400 humans.
Once Enterprise passes through a galactic barrier and Rojan and his fellow Kelvan, Kelinda, set course for the Kelvan home world, he turns his attention to the bridge crew. Kirk can only watch, dismayed, as Uhura, Chekov, and a few lieutenants are distilled. Uhura's look of terror and Chekov's bewilderment create truly tense moments as Kirk realizes he can't help them. While Kirk and the others eventually convince the Kelvans to settle on a nearby uninhabited planet and begin anew, as well as returning crew members back into their natural forms, this is one of the most anxiety-inducing moments of season 2!
3. Kirk plays cat-and-mouse with an unknown enemy in "The Corbomite Maneuver" (S1E02)
This bridge moment is one of the best examples of Kirk's leadership style, as he takes on a fearsome-looking alien called Balok, who claims he is from the First Federation and that Enterprise and her crew are doomed because they destroyed a warning buoy, which Balok considers a hostile act. This becomes one of the greatest cat-and-mouse games of Kirk's life.
Balok claims he will destroy Enterprise after giving them 10 minutes to prepare for their imminent destruction. However, Kirk uses poker strategies, such as calling Balok's bluff several times. He then tells Balok that the ship is carrying a device called "Corbomite," which is so dangerous and powerful that it will destroy Balok's ship if he attacks. Balok tries to use a tractor beam to control Enterprise, but he taxes out his small ship in doing so. Kirk and his navigator, Bailey, beam over to find that Balok is little more than a puppet and the alien is actually friendly and childlike, and that he uses the puppet to frighten people until he can discover their true intentions.