There has been a notable revival of interest in the Star Trek universe buoyed by new productions that can be streamed live. However, the experience can never be as authentic and wholesome if you don’t have a historical view of where everything is coming from. There are numerous characters from different corners of the galaxy and different points in time.
To jump-start your understanding of the Star Trek Universe, you may want to watch Star Trek: The Original Series (TOS) so that everything else will fall in place. Here is our selection of 20 of the best episodes from the original series that we believe capture all the variables for your sampling.
20. The Squire of Gothos (Season 1 Episode 17)
The Enterprise crew come into contact with an omnipotent being, a Trelane, on a planet that should not be inhabited. They are awestruck by the 18th-century environment. The technology on the Enterprise seems to be no match for Trelane’s godlike powers, and he takes quite a bit of pleasure in toying with them.
The self-professed ‘Squire on Gothos’ engages them in a game of wits for his enjoyment where they must disentangle themselves to survive.
19. The Enemy Within (Season 1 Episode 5)
The ship’s transporter malfunctions as Captain Kirk is being beamed back onto the ship, splitting him into two different but identical entities, ideally separating the good side of him from his evil version. It takes an attempt by the evil Kirk to force himself on yeoman Janice Rand for Spock to realize there is a charlatan aboard the Enterprise.
The two are extreme opposites of each other, the evil one being extremely domineering and hostile and the good one too passive and indecisive, even while some of the crew are still stranded outside the ship. Each version tries to dominate the Enterprise. The resulting stalemate puts us in an uncomfortable situation, trying to make up our minds on which version of Captain Kirk is more suited to run the ship.
William Shatner delivers one of his best performances, shifting from indecisiveness to lustfulness, from sorrow to violence portraying human nature’s duality and how it is often contradictory.
18. The Naked Time (Season 1 Episode 4)
The crew becomes exposed to an infection that strips inhibitions and begins to act out their hidden fantasies in one of the series’s most comical episodes. Lieutenant Junior Grade Joe Tormolen, who was part of the landing party, removes his gloves to scratch his nose and gets infected, carrying the infectious polywater agent back to the ship.
The infection drives him to a manic rage buoyed by his insecurities, and he fatally stabs himself. His colleagues Hikaru Sulu and Kevin Riley try to stop him and get infected in the process.
The resultant chaos makes the episode entertaining; Riley starts acting extremely Irish, eventually commandeering the engineering room and shutting off the ship’s engine to serenade the crew with an Irish song. Sulu steals the show as he parades menacingly around the ship bearing a sword and has to be subdued by Spock in the initial display of the Vulcan ‘nerve pinch’ that will become a common move in later episodes.
Captain Kirk struggles to fight against the infection to restore order in the ship. He is struggling to resist his own attraction to Yeoman Rand in the midst of all this.
17. The Enterprise Incident (Season 3 Episode 2)
The Federation sends Captain Kirk and Spock to spy on a Romulan vessel and obtain details about its engineering. We see a rare flirtatious side of Spock as he maliciously seduces the Romulan commander for the sake of the mission. He is not entirely comfortable with the method they used and tells her apologetically that he hopes they have exchanged something more permanent.
The plot is well written as the plan is meticulously executed. The mission is successful as they manage to steal the Romulan cloaking device.
16. Where No Man Has Gone Before (Season 1 Episode 3)
The Enterprise comes across a recording from the USS Valiant that went missing some 200 years ago, which seems to suggest they had to self-destruct to prevent some form of danger.
They proceed to investigate and cross the edge of the galaxy, where they hit a strange barrier that damages their ship, leading to the loss of 9 crew members and knocking out the ship’s psychiatrist Dr. Dehner and helmsman Gary Mitchell.
Gary awakes with godlike powers and unleashes them on the Enterprise crew. Kirk tries to imprison his old friend, so he does not have to use lethal means to subdue him but eventually ends up taking his life.
The episode has impressive action sequences with an emotional ending where Kirk observes that Gary did not ask for what happened to him and entered on record that he died in the line of duty.
15. The Galileo Seven (Season 1 Episode 16)
The shuttlecraft Galileo (the first to be featured in a Star Trek production) is forced to make an emergency landing on Taurus 2 in what was a routine science mission. This is the home of the Taureans; huge apelike beasts. Seven crew members of the Enterprise led by Stock leave the ship to investigate a quasar-like formation dubbed the Murasaki phenomenon.
Meanwhile, the Enterprise is in route to deliver relief supplies to one of the colonies and is wary of a coming ion storm that is bad news in this distant part of the galaxy. A decision must be made on whether to leave the seven for the sake of the many or wait for the Galileo’s return. Captain Kirk squeezes every opportunity from the chain of command to keep looking for the Galileo and his crew.
This episode brings out Spock’s relevance as a leader of the seven, forcing him to give orders in the face of danger as they have to fight heavily armed violent Taureans. He even goes against his Vulcan logical reasoning and makes an illogical gamble when he seems to lose men after following logic.
14. A Taste of Armageddon (Season 1 Episode 23)
The Enterprise crew comes across a society that has evolved beyond vicious combat to protect their infrastructure and conserve their culture. They don’t fight with weapons but engage in combat through accurate simulations where if your number comes up, you are forced into a disintegration chamber.
This system of planets, Eminiar VII, has been in constant conflict for centuries. Captain Kirk escorts a diplomat to them when a few crew members unknowingly find themselves in a building marked to be destroyed and refuse surrender for disintegration. The Enterprise has to intervene at the risk of reverting Eminiar VII back to destructive combat. Kirk suggests that they have merely muted the horrors of fighting.
The episode has action and thrills and leaves us contemplating whether the Enterprise did the right thing for the first time.
13. The Devil in The Dark (Season 1 Episode 25)
The Enterprise is responding to a distress call from the Pergium mining colony on Janus VI. A rocklike creature (Horta) excreting molten lava has been incinerating workers. This episode addresses the fear of the unknown.
Spock performs a Vulcan mind-meld for the very first time. He can communicate with the creature and realizes Horta’s intentions were not malicious. Rather it was the miners who had done it wrong by destroying its eggs, and it was just trying to protect them.
Captain Kirk and Spock convince the miners to coexist with the creature, which may be useful for their mining.
12. Arena (Season 1 Episode 18)
This is the first conflict the Starfleet ever engages in with the Gorns. The Enterprise is chasing a Goran ship after discovering they have obliterated the Cestus III outpost without provocation. The chase takes them to an unexplored area of space where their ships are disabled by the powerful Metrons, guardians of this sector of space.
To manage the possible destruction that may arise from a conflict, the Metrons pit the captains of the two ships against each other in a battle to the death where the survivor is allowed to go free and the loser will be obliterated along with their ship.
The captains are beamed to a desert planet that should have enough resources for them to fight each other as their crews watch helplessly from their disabled vessels. The Goran captain is physically stronger, forcing Captain Kirk to rely on his wits and every available tool to survive.
11. The Menagerie: Part 1 and 2 (Season 1 Episodes 11 and 12)
This is a flashback episode that takes us to a time before Captain James Tiberius Kirk took the helm of the Enterprise. First Officer Spock commandeers the Enterprise with falsified recordings of Captain Kirk’s voice and sets the vessel on a course to Talos IV under strict quarantine and should not be visited. He takes his former commander, Captain Christopher Pike, who is injured and disabled, with him.
Captain Kirk gives chase in a Starbase shuttlecraft, and Spock lets him into the Enterprise after confirming the shuttlecraft doesn’t have enough fuel to return to the Starbase. He goes on to surrender and requests to be put on trial immediately to explain the reasons for his actions.
He produces a recording of their earlier mission on Talos IV for his defense, which shows what the Talosians (an alien race of telepaths with large heads) had done with the survey ship Columbia survivors that crashed on the planet earlier.
The plan is to bring his former commander, Captain Christopher Pike, back to Talos IV to reunite him with Vina so that he can live out the rest of his life in the illusion of normalcy with help from the Talosians illusions.
10. Journey to Babel (Season 2 Episode 10)
The Enterprise is on a mission to transport ambassadors of the United Federation of Planets to a conference in Babel where they discuss the merits of the possible inclusion of the Coridan System in the Federation. Natural occurrences of the rare mineral Dilithium (used to fuel warp drives in ships) in the Coridan system remain protected.
It is one of the few times the Federation’s founding members are all together on the screen, and new species like the Andorians and Tellarites are introduced. We also get an insight into Spock’s family relations as his father, Sarek, is the Vulcan ambassador and his mother is also present.
The Tellarite ambassador Gav is murdered in a Vulcan-style execution after a major disagreement with Sarek over unauthorized mining of dilithium in the Coridan System by Tellarite ships. All suspicion naturally turns to Sarek, who suffers a cardiac attack and has to be treated using Spock’s blood.
The ship is also under attack from an unknown vessel that seems to be receiving communication from within the Enterprise.
9. The Corbomite Maneuver (Season 1 Episode 10)
The Enterprise is facing imminent destruction from a powerful First Federation Ship called the Fesarius because they have trespassed into First Federation territory and destroyed their boundary marking buoy.
Captain Kirk is forced to resort to a bluff, seeing the Enterprise is no match for the Fesarius. He tells Balok, the commander, that the Enterprise possesses a powerful substance called Corbomite that will reflect any energy projected against the ship back to its source with equal force. He also feigns not to care what happens to the Enterprise and its crew once the Fesarius attacks.
This forces Balok to reconsider his attack and leads to a turn of events that would see them being invited aboard the Fesarius.
8. The Doomsday Machine (Season 2 Episode 6)
This is the episode where the Starship Enterprise faces a powerful machine from a different galaxy capable of destroying entire planets. They find themselves facing the machine after responding to a distress call from the USS Constellation while investigating a surge in star system destruction. The Constellation had been damaged while trying to attack the Doomsday machine.
The machine comes for them as they are trying to repair the Constellation’s viewscreen and weapons and shields, forcing the Enterprise to fight back in what seems to be a losing battle as their phasers don’t seem to have any effect on the machine.
It takes a lot of sacrifice of lives and ships to fight against the doomsday machine.
7. Let That Be Your Last Battlefield (Season 3 Episode 15)
The USS Enterprise intercepts signals from a Federation shuttlecraft reported having been stolen while on a mission to help decontaminate the atmosphere in Ariannus, a planet plagued by bacteria.
They bring the craft onboard along with its alien pilot, a humanoid who is black on one side and white on the other. He identifies himself as Lokai, a political refugee from the war-torn planet Charon. They realize they are being pursued by another spacecraft that happens to be ferrying another alien from Charon named Bele, who has apparently pursued Lokai to take him back to face trial for his war crimes.
The two have a charged argument, and at some point, Bele takes control of the Enterprise, forcing Captain Kirk to engage self-destruct to bring him back to his senses. They all proceed to Ariannus to complete the mission. The episode ends with a lesson as they find Charon deserted, with no life, possibly due to civil war. To the enterprise crew, the two aliens seem similar, but they harbored much hate due to perceived differences.
6. The Trouble with Tribbles (Season 2 Episode 15)
The Enterprise is docked at the Deep Space Station K-7 on guard duty for a quadrotriticale grain shipment. It is suspected that visiting Klingons may disrupt their delivery to an Earth colony. The crew enjoys this as shore leave, so does the crew of a Klingon ship.
Lieutenant Uhura purchases a tribble (an alien species that looks like a ball of fluff and purrs) from an interstellar trader. They later discover that tribbles are born pregnant and multiply at a very high rate. The starship is soon filled with tribbles that threaten to consume all their food, including the grain shipment they are protecting.
The tribbles end up taking one for the Earth colony, as they uncover that the grain was poisoned.
5. Amok Time (Season 2 Episode 1)
Captain Kirk disobeys orders to represent the Federation at the inauguration of the new president of the planet Altair VI after McCoy tells him that Spock’s symptoms will kill him within eight days if not treated.
Spock explains he is going through pon farr, a phase in the Vulcan reproductive cycle where an adult male has to mate, or they will die. Kirk risks his career by diverting the ship to Vulcan to facilitate this.
To fulfill the pon farr, Spock has to take T’Pring as his mate since they were bonded as children. T’Pring prefers another mate instigates a physical challenge to determine who will be her mate. Using Vulcan logic, she surprisingly pits Captain Kirk against Spock to spare her beloved Stonn.
4. Mirror Mirror (Season 2 Episode 4)
An ion storm causes a transportation problem which lands Captain Kirk, Dr. McCoy, Scott, and Uhura in a mirror universe, swapping them with their evil counterparts from that universe. The new world is filled with suspicion, betrayal, dominance, and violence, and the Federation is an evil empire.
The crew must find a way to fix the anomaly without spooking the evil Spock from this universe who does not understand their hesitation to attack the Halkans for refusing to allow the Federation to mine dilithium from their planet. Kirk orders them to the sick bay so they can plan their return privately.
Spock is also holding their doppelgangers in sick bay at the same time on the original Enterprise, quite amazed by their new demeanor.
3. Balance of Terror (Season 1 Episode 14)
The Enterprise faces off with a Romulan ship that has a cloaking device that renders it invisible. The ship has been attacking Earth outposts in the Romulan neutral zone declared in the peace treaty that ended the Earth-Romulan war a century ago.
Humans and Romulans have never seen each other before. The resemblance of the Romulan ship’s crew to Vulcans raises discord in the Enterprise for a fleeting second as Spock’s loyalty is questioned by Lieutenant Stiles.
The episode’s highlight is the cat and mouse games and the tactical proficiency in display by both captains as they try to outmaneuver each other.
2. Space Seed (Season 1 Episode 22)
The Enterprise encounters the long-lost Earth vessel USS Botany Bay drifting in space. They find 84 humans who have been in suspended animation for over 200 years, 72 of whom are still alive.
Captain Kirk decides to stow the Botany Bay to Starbase 12 so the survivors can be attended. Historian Lieutenant Marla McGivers identifies their leader, Khan Noonien Singh, a 20th-century human selective breeding experiment product, and is awestruck.
Khan influences McGivers to beam him onto the Botany Bay, where he wakes up his colleagues, and they try to take over the Enterprise.
1. The City on The Edge of Forever (Season 1 Episode 28)
McCoy inadvertently alters the future by going back in time while intoxicated from a sedative he was administering to Lieutenant Sulu. This triggers a series of unfortunate events. Captain Kirk and Spock follow him through to try and restore the timeline.
The mission involves living in the 20th century for a while as they try to figure out how to rectify the situation before McCoy appears. During this period, Captain Kirk falls in love with the subject of the altered future, Edith Keeler.
The combination of adventure and emotion in this episode makes it one of The Original Series’s most captivating installments.