Best 'Star Trek' episodes

- IMDb user rating: 7.7
- Season 3, Episode 7
- Director: Marvin J. Chomsky

The seventh episode of the third season of "Star Trek" once again pitted the Enterprise crew against the brutal Klingons. A being of pure energy creates confusion between the two factions, inserting false memories and creating conflict—in one instance, Chekov becomes aggressive towards the Klingons for killing a brother of his that never existed in the first place. The Klingon character of Kang, who originated from this episode, would return in the "Deep Space Nine" and "Voyager" shows decades later.

- IMDb user rating: 7.7
- Season 2, Episode 17
- Director: James Komack

Sometimes, "Star Trek" likes to incorporate time travel to create period-piece episodes, but in the case of Season Two, Episode 17, Kirk, Spock, and McCoy land on a planet that emulates 1920s Chicago gangster culture. With Tommy guns, fedoras, and pulpy 1920s dialogue, this fun episode goes through many of the classic gangster tropes. It's a memorable episode, particularly to writer-director Quentin Tarantino, who in the late 2010s wanted to direct a rated-R "Star Trek" movie inspired by the episode.

- IMDb user rating: 7.7
- Season 1, Episode 3
- Director: James Goldstone

The second pilot of "Star Trek" is titled after the famous mantra of the franchise, though "Where No Man Has Gone Before" was aired as the third episode of the first season. This episode was meant to introduce viewers to the general concepts of "Star Trek," with a standard mission gone awry—as a result, helmsman Gary Mitchell gains psychic and telekinetic powers, proclaiming himself to be god-like. "Above all else, a god needs compassion," Kirk says in one iconic scene when describing Mitchell's violent actions. As pivotal as the episode is, it lacks mainstay characters like McCoy and Uhura.

- IMDb user rating: 7.8
- Season 1, Episode 24
- Director: Ralph Senensky

Spock is often paired with short-term romantic interests in "Star Trek," and Episode 24 of the first season features one in the character Kalomi. Spock reunites with this botanist from his past on an away mission—he, Kirk, and McCoy beam down to a colony to find that all of its inhabitants are affected by spores that invoke an overly positive and lethargic attitude. For the half-human, half-Vulcan character Spock, it was another opportune time for him to explore his emotions as he found himself under the same influence.

- IMDb user rating: 7.8
- Season 1, Episode 4
- Director: Marc Daniels

The fourth episode of the show as a whole let the cast members let loose and act out of character. It starts with Spock and a lieutenant observing frozen corpses in an abandoned research facility—after which they inadvertently bring some sort of sickness to the Enterprise that makes everyone affected act irrationally. Spock sheds tears and has an intimate moment with Nurse Chapel, but in a sillier (and iconic) scene, a shirtless Sulu runs amok with a sword.

- IMDb user rating: 7.9
- Season 1, Episode 19
- Director: Michael O'Herlihy

The 19th episode of "Star Trek" Season One is a time-travel story, with the Enterprise finding itself above 1960s Earth. A U.S. Air Force pilot named John Christopher flies up to identify the ship, only to be beamed up by the crew. What ensues is a race to scrub all evidence of the Enterprise's visit to the 1960s while containing Christopher, all while trying to return home. In terms of "Star Trek" lore, the Enterprise's method of returning to the future is used again in "Star Trek IV: The Voyage Home" and referenced in "Star Trek: Picard."

- IMDb user rating: 7.9
- Season 1, Episode 18
- Director: Joseph Pevney

Episode 18 of "Star Trek" showcases some of Kirk's physical combat abilities as he is forced to fight a member of the reptile species known as the Gorn. The fight scene between Kirk and the Gorn captain was shot at the Vasquez Rocks, a location used so frequently by the franchise that it is nicknamed the "Star Trek Rocks." Modern audiences have mocked and parodied the fight scene, but its iconic status has never been disputed.

- IMDb user rating: 8.0
- Season 3, Episode 9
- Directors: Herb Wallerstein, Ralph Senensky

Season Three, Episode 9 of "Star Trek" begins with the Enterprise searching for its sister ship, the Defiant. Unfortunately, the Defiant's crew had perished somehow, and the Enterprise crew find themselves up against interdimensional beings known as the Tholians. As they create an energy web around the entire Enterprise, Kirk is believed lost and the crew members begin to fall to the same madness that led to the Defiant crew's demise. The plotlines of the Defiant and the Tholian Web are followed up in the prequel show "Enterprise," in the 2005 two-part episode "In a Mirror, Darkly."

- IMDb user rating: 8.0
- Season 2, Episode 24
- Director: John Meredyth Lucas

In a premise that still rings true today due to the prevalence of artificial intelligence, Season Two, Episode 24 features a computer named M-5, designed and built to handle all ship functions. Unsurprisingly, M-5 begins to turn malevolent, effectively trying to replace Kirk as the captain and attacking other Federation starships. "Computers make excellent and efficient servants, but I have no wish to serve under them," Spock tells Kirk at one point.

- IMDb user rating: 8.0
- Season 1, Episode 23
- Director: Joseph Pevney

Episode 23 of Season One features a rather unique sci-fi concept—a planet that fights war through virtual means. Kirk lands on a planet that is in conflict with another planet, and the long war between the two is fought in a simulation; when someone "dies" in the simulation, they are killed in real life. Unfortunately for Kirk, the Enterprise is destroyed in the simulation, but Kirk naturally refuses to destroy his ship and crew. Despite the dire premise, the resolution of the episode has fans believing it to be an overall optimistic story.

- IMDb user rating: 8.0
- Season 1, Episode 10
- Director: Joseph Sargent

The 10th overall episode of "Star Trek" was the first to be shot after the pilot episode, and it features a memorable encounter with an alien named Balok (featured in the closing credits of the show). Balok claims that he is all-powerful and will destroy the Enterprise, giving the crew 10 minutes, but Kirk calls Balok's bluff. Summing up the lesson of the episode, Kirk remarks: "You know the greatest danger facing us is ourselves, an irrational fear of the unknown. But there's no such thing as the unknown—only things temporarily hidden, temporarily not understood."

- IMDb user rating: 8.1
- Season 3, Episode 23
- Director: Marvin J. Chomsky

Season Three, Episode 23 of "Star Trek" features some recurring tropes of the show, such as time travel and Spock having a brush with romance. The main trio of Kirk, Spock, and McCoy each end up in two distant time periods of a planet. Spock and McCoy encounter a woman named Zarabeth, whom McCoy is suspicious of and Spock falls in love with rather quickly. While most time-travel episodes center around Earth, using this narrative device to explore the past of an alien planet was thought to be unique by fans.

- IMDb user rating: 8.1
- Season 1, Episode 26
- Director: John Newland

Episode 26 of Season One utilizes the Klingons as the main foes, with "Errand of Mercy" depicting the beginning of a war between the Federation and the Klingon Empire. Kirk and Spock visit a neutral planet near the Klingon Border called Organia and attempt to convince its people to resist Klingon forces in this Cold War allegory episode. While the peaceful Organians appear to be primitive at first, they soon surprise Kirk and Spock as well as the Klingons. The main antagonist, the Klingon named Kor, returns in "Deep Space Nine."

- IMDb user rating: 8.1
- Season 1, Episode 12
- Directors: Robert Butler, Marc Daniels

Spock is under court martial in Season One, Episode 12, in this conclusion to the previous episode. This second part features the psychic Talosian aliens more heavily, as well as the character of Number One, who is portrayed by Roddenberry's second wife, Majel Barrett. With the previous episode establishing Captain Pike's tragic injuries, this second half provides a happier ending for the former captain of the Enterprise.

- IMDb user rating: 8.2
- Season 1, Episode 11
- Directors: Marc Daniels, Robert Butler

Season One, Episode 11 revisited events from the unaired pilot episode of "Star Trek," titled "The Cage." That pilot had featured Captain Pike (Jeffrey Hunter) instead of Kirk, but "The Menagerie" clarifies that Pike was the captain of the Enterprise before Kirk. At this point in time, Pike has been horrifically injured, bound to a chair, and only able to communicate through beeps. Pike and Spock once again end up on the planet Talos IV for some unfinished business, and the episode utilizes footage from "The Cage" extensively as flashbacks for budgetary reasons.

- IMDb user rating: 8.3
- Season 1, Episode 25
- Director: Joseph Pevney

"Star Trek" is arguably its most memorable when it teaches viewers about compassion and pacifism, and Episode 25 of the first season very much demonstrates this. Kirk, Spock, and McCoy begin to assist a mining colony dealing with a creature responsible for killing workers. Upon encountering the creature, the main characters begin to understand its nature better, and instead spare it and cure it, facilitating a symbiotic relationship between the creature and the miners.

William Shatner considers the episode one of his favorites, but behind the scenes, Shatner's father passed away during production, necessitating the temporary use of a body double while he attended his father's funeral.

- IMDb user rating: 8.4
- Season 3, Episode 2
- Director: John Meredyth Lucas

The writers of "Star Trek" loved to use sudden irrational behavior by the characters as plot devices, and Episode 2 of the third season features Captain Kirk going off the rails. The Enterprise is on a secret mission to steal a Romulan cloaking device, and they encounter a female Romulan commander who eventually takes an interest in Spock. Kirk acts erratically through the episode and is even declared unfit to captain, leading to a dramatic episode overall.

- IMDb user rating: 8.5
- Season 2, Episode 10
- Director: Joseph Pevney

Some significant characters in "Star Trek" lore make their first appearance in Episode 10 of Season Two, as Spock's parents Sarek and Amanda (the latter being human) feature heavily. Sarek, an ambassador, is wrongly accused of murdering a foreign dignitary, and it's up to Spock to clear his name. While Sarek and Amanda made more appearances in future "Star Trek" media, this episode is their only appearance in the original series.

- IMDb user rating: 8.6
- Season 2, Episode 1
- Director: Joseph Pevney

The season premiere of "Star Trek" Season Two introduced concepts that would permeate larger popular culture. Spock's bizarre behavior leads the characters to learn about pon farr, a physiological phenomenon related to Vulcan mating. Viewers meet Spock's betrothed, a Vulcan named T'Pring, and the iconic Vulcan salute is used for the first time in this episode. The events culminate in a fight between Kirk and Spock, with the scene and its incidental music parodied in movies like "The Cable Guy" and shows including "Futurama."

- IMDb user rating: 8.7
- Season 2, Episode 6
- Director: Marc Daniels

Catastrophic destruction is the main threat of Season Two, Episode 6, aptly titled "The Doomsday Machine." The Enterprise finds that one of its sister ships, the Constellation, has been heavily damaged by a machine capable of destroying planets. Matt Decker, one of the ship's survivors, goes on a mad campaign against the machine, jeopardizing the Enterprise in the process. While Decker doesn't make it by the end of the episode, his son Willard Deckard is a main character in 1979's "Star Trek: The Motion Picture."

- IMDb user rating: 8.7
- Season 1, Episode 22
- Director: Marc Daniels

Episode 22 of the first season introduced perhaps the most recognizable villain in all "Star Trek" media: Khan Noonien Singh, portrayed by Ricardo Montalbán. A genetically engineered man from the past, Khan attempts to lead his people in overthrowing the Enterprise. While Khan was thwarted and exiled, he would later return in "Star Trek II: The Wrath of Khan," widely thought to be the greatest "Star Trek" movie in the franchise.

- IMDb user rating: 8.8
- Season 2, Episode 15
- Director: Joseph Pevney

"Star Trek" isn't just political allegory and technobabble—there has to be levity sometimes as well. Enter the tribbles, cute little fuzzy creatures that create a problem for the Enterprise, as a tribble found in a space station begins multiplying rapidly. Meanwhile, conflict arises between Enterprise crew members and Klingons, culminating in a brawl in the space station. For the 30th anniversary of "Star Trek," an episode of "Deep Space Nine" titled "Trials and Tribble-ations" revisited the events of this episode, digitally inserting the "Deep Space Nine" cast into the events of the original episode.

- IMDb user rating: 8.8
- Season 1, Episode 14
- Director: Vincent McEveety

Episode 14 of the first season of "Star Trek" is essential viewing, as it introduces the antagonistic Romulan race, a staple of the "Star Trek" universe. The centerpiece of this action-packed episode is a cat-and-mouse game between the Enterprise and a Romulan vessel with cloaking capabilities, leading to exciting and tense encounters. It's an episode full of high emotion that explores the effect and ramifications of war, with Kirk and the Romulan commander speculating that in another life, perhaps they could have been friends.

- IMDb user rating: 9.0
- Season 2, Episode 4
- Director: Marc Daniels

Episode 4 of Season Two of "Star Trek" had the first look into another dimension within the lore, often referred to as the Mirror Universe. In this reality, the Federation is instead the Terran Empire, which is aggressive and militaristic in nature. The USS Enterprise is instead the ISS Enterprise, torture in the Agony Booth is the main form of discipline, and Mirror Spock famously fashions a goatee. The Mirror Universe has become a mainstay in most "Star Trek" shows, and the use of a beard to signify an evil doppelganger is an often used and parodied trope.

- IMDb user rating: 9.2
- Season 1, Episode 28
- Director: Joseph Pevney

In quite possibly the most famous episode in the entire "Star Trek" franchise, Captain Kirk faces an unimaginable moral dilemma. A chase for an unwell McCoy leads to history being changed, and the Enterprise crew members find themselves in Depression-era New York City to repair the damage. Kirk falls in love with a social worker named Edith Keeler, but to his dismay, he discovers that for the timeline to be restored, Edith must be allowed to die. The tragic ending, Shatner's performance, high regard from both the cast and crew of "Star Trek," and multiple awards solidified "City" as the most celebrated "Trek" episode of all time.

Data reporting by Luke Hicks. Copy editing by Tim Bruns. Photo selection by Clarese Moller.