Star Trek has been on the air in some form on and off since 1966. There have been eight live-action series and three animated series that have brought the adventures of Starfleet and the United Federation of Planets to fans. While Star Trek always remains popular, not every episode of each series is created equally.
Some episodes have reached such critical acclaim they are mentioned among not just the greatest episodes of Star Trek but also the greatest episodes of television ever. Each series has produced gems that get fans talking and keep them coming back for more Star Trek.
11 The City On The Edge Of Forever - The Original Series
While there are many options for The Original Series, "The City on the Edge of Forever" is one that still gets fans talking more than 50 years after its original airing. Kirk and Spock are thrust into the past to stop a deranged McCoy from altering the future. This inadvertently leads to the Nazis winning World War 2.
Kirk falls in love with a woman from the time but realizes he must let her die to not change history. And he has to stop Bones from saving her as well. It restores history but remains one of the most heartbreaking and gutwrenching episodes as a genuinely good person has to stop another genuinely good person from performing a heroic act or else the ultimate villains will win in history.
10 Yesteryear - The Animated Series
Building on "The City on the Edge of Forever," The Animated Series episode "Yesteryear" brings back the Guardian who sent Kirk and Spock back in the past. This episode focuses on Spock's past, and while there has been debate over the years about whether The Animated Series should be considered canon, this episode introduces aspects that are later proven to be canon.
The bullies that pick on Spock in the 2009 film Star Trek and Spock's house in the second season of Discovery are both introduced in this episode. This is an essential television episode for any Spock fan.
9 The Best Of Both Worlds: Parts 1 & 2 - The Next Generation
Prior to season three of The Next Generation, Star Trek avoided season-finale cliffhangers. But that changed with the season three finale and season four premiere "The Best of Both Worlds: Parts 1 & 2". The Borg are on a quest to assimilate Captain Picard turning him into the public face of their campaign, Locutus of Borg.
The Enterprise crew has its own reckoning in these two episodes as they struggle with their captain being taken hostage and assimilated. It also demonstrates why Riker deserves a promotion to captain and why it's so important for the Enterprise that he keeps rejecting the promotions offered to him. This may be the best drama any Star Trek series has produced.
8 Trials And Tribble-ations - Deep Space Nine
Tribbles always make Star Trek more fun, and they are able to bring together two successful series despite The Original Series and Deep Space Nine being polar opposites in tone. "Trials and Tribble-ations" features the DS9 crew traveling through time to interact with Kirk's crew on board the Enterprise.
This episode is campy, and there's barely enough plot to make the interactions between the two shows work, yet it somehow works better than anyone could have imagined. This episode was dreamed up to just be fan service, but the cast and crew blend everything so well with the historical footage that it remains a groundbreaking episode.
7 Scorpion - Voyager
The third season finale of Voyager is one of the most pivotal in the series as it provides the first real appearance by the Borg in the Delta Quadrant. The episode, "Scorpion," also features the debut of a character who would go on to be a fan favorite across multiple series: Seven of Nine.
The episode demonstrates the Borg see another species as a bigger threat than them and leads to an uneasy alliance between the Borg and the Voyager crew. The episode is a cliffhanger that leads to the premiere of season four and the crew rescuing Seven from the Borg collective as the Voyager learns the Borg will still attack them just like a scorpion.
6 In A Mirror, Darkly - Enterprise
The mirror universe is almost universally beloved among Star Trek fans, so it made sense for Enterprise to revisit it during the show's fourth season. The two-part episode "In a Mirror, Darkly," follows the mirror version of Captain Archer's Enterprise crew as they explore on behalf of the Terran Empire.
This episode not only links back to The Original Series with the mirror universe theme but finds a way to connect to Deep Space Nine with the Defiant. While this two-parter doesn't connect to the main universe, it's a treat to see the cartoonish evil version of this crew without the obvious plot of trying to get back home.
5 What's Past Is Prologue - Discovery
In another series where the best episode is set in the mirror universe, Discovery takes a different tactic once it reaches the other side. In "What's Past Is Prologue," Captain Gabriel Lorca is revealed to have been the former Emperor of the Mirror Universe and is looking to return to his throne.
Lorca had disappeared to the Prime Universe but with the help of the Discovery's crew, he found his way back home. It sets up the Captain the crew all thought they could trust as the season's big villain and Jason Isaacs' charisma shines as he's playing Lorca.
4 Crisis Point - Lower Decks
The comedic, animated version of Star Trek brings some of the best rank-and-file characters to the franchise. However, Lower Decks really shines when Beckett Mariner and her mother, Captain Dawn Freeman, come head to head in their disagreements about Starfleet. This is exactly what happens in the season one episode, "Crisis Point."
Mariner hijacks a holodeck program run by her friend Ensign Boimler and turns it into a movie that allows her to work through her anger. She casts herself as a villain and takes out her anger on the crew of the Cerritos. Eventually, she finds the exercise therapeutic when she ends up fighting herself. It's the best episode for Mariner's character development.
3 The Last Generation - Picard
While Picard took a while to find its legs, season three demonstrated how good modern Star Trek can be when the shows are given time. The series finale sends Picard off on the highest possible note for the series. The Next Generation crew is back aboard their Enterprise as they take on a new type of Borg.
This series brings back the crew Star Trek fans love to battle its best villain which has evolved how it attacks the Federation. Old and new crews work together to save Starfleet and the galaxy. It is quite possibly the best series finale for any of the Star Trek series.
2 Supernova - Prodigy
This two-part episode from Star Trek's third animated series really helped develop the series as one that can introduce children to Star Trek. In "Supernova," The crew who escaped from a penal colony are now endangering Starfleet with their ship. They have to find a way to serve the Federation despite not being a part of it and learn about self-sacrifice.
Unfortunately, despite being greenlit for a second season, Paramount Plus chose to stop airing Prodigy. The second season is still being produced and Paramount is looking to sell it to a different distributor. Maybe Prodigy will get a chance to improve upon this episode.
1 Memento Mori - Strange New Worlds
The fourth episode of Strange New Worlds is where the series really finds its legs. "Memento Mori" introduces the Gorn, a popular alien species first introduced in The Original Series. The crew of the Enterprise and the Gorn engage in a high-octane battle that features both perseverance and trauma.
The series had been trying to strike a balance between conflict and provoking thought. It helps this version of Pike, Spock and the crew find their way and show their rawer side to the viewers. This is the episode where many fans decided Strange New Worlds was the best of the new Trek.