Few franchises have enjoyed the popularity and longevity that the beloved sci-fi Star Trek has. It's the longest-running franchise in American TV history, with no signs of wrapping up anytime soon, and has been hugely influential in pop culture. The original series was created by Gene Roddenberry and followed the crew of the U.S.S. Enterprise as they explored the galaxy in the 23rd century, with subsequent series following a similar premise but with different ships and crews and set in different times, as well as a number of films.

With hundreds of episodes in the franchise, choosing the best is a daunting task. At its best, the series told compelling, emotional stories, sometimes very human ones, despite the focus on the future and other species. The best episodes also often feature themes and plot devices like alternate timelines and time travel. But no matter the story, the one thing they all have in common is compelling storytelling with characters at the center.

20 "Supernova"

'Prodigy,' Season 1, Episode 19

In the two-part Prodigy episode “Supernova,” the crew was surrounded by the Federation armada, and a Living Construct was unleashed, threatening to destroy all of Starfleet. The crew turned to other allies for help by putting out a distress call, which drew other ships to the area who helped deflect blasts and beam Starfleet personnel off of their ships under attack, but other Starfleet ships also responded, putting them in danger from the Construct, as well.

“Supernova” was a standout episode of Prodigy and a fitting way to end its first season, with high stakes for Starfleet. The intense episode also came with plenty of emotional moments, especially as it came to its conclusion in the second part with the destruction of the Protostar as the best option to defeat the Construct. The episode had huge implications for the series moving forward and felt like it could serve as a series finale, although that fortunately wasn’t the case.

Star Trek: Prodigy can be streamed on Netflix in the U.S.

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19 "Blink of an Eye"

'Voyager,' Season 6, Episode 12

In “Blink of an Eye,” Janeway (Kate Mulgrew) and the crew became trapped in the orbit of a primitive planet which then started to evolve at an amazingly fast pace, allowing them to witness much of its history, while its citizens were in awe of the Voyager in the sky above them. As time passed on the planet, generations of its citizens were inspired by the ship to create art and even establish religion.

“Blink of an Eye” was a fascinating episode about a distant planet, but it also echoed the impact Star Trek has had on everything from pop culture to technology. Daniel Dae Kim, best known for his roles on Lost and Hawaii Five-Oh, had a memorable role as Gotana-Retz, an astronaut from the planet who made it up to the Voyager and served as an ambassador until he was able to return, and 50 years had passed on the planet.

18 "The Trouble with Tribbles"

'Star Trek' Season 2, Episode 15

In the TOS episode “The Trouble with Tribbles,” Uhura (Nichelle Nichols) got an interesting new pet, a small furry animal called a tribble, which was born pregnant and therefore reproduced at an astounding rate, leading the Enterprise to quickly become overrun with the furry creatures. On top of that, they didn’t get along well with Klingons. Meanwhile, the Enterprise is tasked with protecting a space station receiving a crucial shipment of grain, and the crew uncover a Klingon plot to poison it.

Fan-favorite “The Trouble with Tribbles” is among the most famous episodes of TOS, in part because it had all the elements of classic Star Trek—it successfully combined the funny, lighthearted plot of the Gremlin-like tribbles with the larger dramatic themes and conflicts of the show. The plots of the tribbles and poisoned grain came together in the end when the crew discovered a number of tribbles died after eating the grain.

17 "Balance of Terror"

'Star Trek,' Season 1, Episode 14

In this Season 1 episode from the original series, the Enterprise engages in a game of cat-and-mouse with a Romulan ship while investigating the destruction of four outposts along the neutral zone in “Balance of Terror,” with the Romulans suspected of being responsible. The Romulans had a powerful weapon in their possession, and their commander saw many similarities between himself and Kirk (William Shatner). The episode was revisited in Strange New Worlds episode “A Quality of Mercy,” which explored its events through an alternate future.

On top of just being a great episode, “Balance of Terror” was also notable for introducing the Romulans, an offshoot of Vulcans and one of the show’s most formidable enemies. The episode dealt with the theme of bigotry, a common one throughout the franchise, and presented an exciting submarine-like chase. Given its role in Strange New Worlds decades later, its impact on the franchise is clear, and the follow-up episode served to illustrate the differences between Pike (Anson Mount) and Kirk.

16 "Devil in the Dark"

'Star Trek,' Season 1, Episode 25

In “Devil in the Dark,” Kirk and Spock (Leonard Nimoy) answer a distress call on another planet to find dozens of workers in a mining facility have been killed by an unknown creature. But the creature, called a Horta, turned out to be more intelligent than they originally thought and was a mother trying to protect her babies. Her eggs were being accidentally destroyed by the miners, who thought they were mineral formations.

“Devil in the Dark” proved to be more than a simple monster story, it was really quintessential Star Trek, with a conflict rooted in a misunderstanding resolved through peaceful means. The episode also dealt with the themes of environmentalism, colonization, the fear of the unknown and misconceptions of an enemy and their motives. It is also memorable for some of its classic moments and dialogue, including the first instance of what would become McCoy’s (DeForest Kelley) catchphrase.

15 "Yesteryear"

'The Animated Series,' Season 1, Episode 2

“Yesteryear” from The Animated Series saw Spock return from a trip back in time only to find something had been changed accidentally. An Andorian was in his place aboard the Enterprise, as Spock had died as a young child during kahs-wan, a maturity ritual. To set things right, the Guardian from another notable Star Trek episode, “The City on the Edge of Forever,” appeared and sent Spock back in time to his childhood.

The Animated Series may not be considered the best Star Trek had to offer, but it still had some standout episodes. “Yesteryear” was a great Spock-centered episode dealing with his past, and its ties to “The City on the Edge of Forever” were an added bonus tying it back to The Original Series. It was a great time-travel episode, as Spock realized the person who saved his life during the kahs-wan as a child was actually himself.

Star Trek: The Animated Series can be streamed on Prime Video in the U.S.

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14 "The Last Generation"

'Picard,' Season 3, Episode 10

The Paramount+ series Picard brought back Captain Jean-Luc Picard (Patrick Stewart) and his crew. In the series finale of Picard, “The Last Generation,” the titular captain’s crew from The Next Generation, along with crews new and old, took on the Borg from the Enterprise. Starfleet was under the Borg’s control and the Queen was out for revenge on the crew, resulting in the greatest threat they had ever faced. Despite the risk of becoming Locutus, Picard focuses on prioritizing and saving his son.

“The Last Generation” was the sendoff Picard and his Enterprise crew deserved. It felt very much like an ending for The Next Generation, with some Easter eggs throughout and, more importantly, great emotional moments as the crew recognized the magnitude of the threat they were dealing with and faced the possibility that some of them, or all, might not survive it. The episode also hinted at what may be yet to come in the future of the franchise.

13 "Duet"

'Deep Space Nine,' Season 1, Episode 19

In “Duet,” a Cardassian named Marritza (Harris Yulin) arrives at Deep Space Nine, suffering from Kalla-Nohra, a disease which suggests he had spent time in a labor camp. Suspicious that he had a role in the Cardassian occupation of Bajor and was lying about who he was, Kira (Nana Visitor) begins to investigate him. He then claimed to be Gul Darhe’el, a leader in charge of the labor camp, a claim which was found to be false. Marritza was trying to get caught.

“Duet” was a strong episode in the series’ first season which delved into the politics of Star Trek and Deep Space Nine in particular and had multiple twists before arriving at the truth about Marritza and his motivations. The episode was also a story about remorse and vengeance, with Marritza seeking to atone for his actions while Kira was seeking vengeance, only to change her mind in the end, and for someone else to take matters into their own hands.

12 "In the Pale Moonlight"

'Deep Space Nine,' Season 6, Episode 19

“In the Pale Moonlight” saw Sisko (Avery Brooks) trying to goad the Romulans into joining the Federation in a war against the Dominion, with the chances of losing becoming increasingly likely. He turned to Garak (Andrew J. Robinson), a former spy, for help to fabricate evidence of a Dominion plot to invade the Romulan Star Empire and giving it to a Romulan senator. When the senator realized the evidence was fake, Garak killed him. The episode is framed with Sisko recounting the events in his log.

Deep Space Nine is often regarded as a great Star Trek show with a reputation for darker storylines, and when it was at its best, it was often exploring stories like that of the Dominion War. “In the Pale Moonlight” was no exception. The episode was controversial yet memorable, still regarded now as one of the series’ best, with its theme of morality not always being black and white. It was also a great episode for Sisko especially.

11 "The Drumhead"

'The Next Generation,' Season 4, Episode 21

After an explosion aboard the Enterprise damaged the warp core and injured several crewmembers in “The Drumhead,” evidence of sabotage pointed to a Klingon Exchange officer, thought to be a spy for Romulans. The incident led to a retired admiral boarding the Enterprise to investigate, and she became increasingly sure the Klingon wasn’t the only one involved, ultimately leading to Picard being accused of treason. The episode was directed by Jonathan Frakes, known for playing Riker.

“The Drumhead” was a compelling episode, with its courtroom-drama structure and themes of espionage and, more importantly, paranoia, as the admiral’s investigation became increasingly absurd. Courtroom dramas had been done in Star Trek before, but this was among the best of them. It was also a notable episode for Picard, as he expressed his concerns about how the investigation was playing out and ended up being one of its subjects.

10 "In a Mirror, Darkly"

'Enterprise,' Season 4, Episodes 18 and 19

In the two-part Enterprise episode “In a Mirror, Darkly,” set in the Mirror Universe, Commander Archer (Scott Bakula) launches a mutiny against Captain Forrest (Vaughn Armstrong) on the Enterprise. After the Enterprise was destroyed, the crew was stranded aboard the USS Defiant, a ship from a parallel future universe, and Archer declared himself captain and intended to use the ship in a coup against the emperor. The episode was intended as a sequel to TOS episode “The Tholian Web.”

Enterprise finally realized its potential with “In a Mirror, Darkly,” the standout episode of the series, and the most popular one. It was an entertaining exploration of the Mirror Universe, a concept Star Trek fans quite enjoyed, with the evil counterparts of the series essentially providing a completely different show, devoid of the morality viewers were used to. The episode was also a great way to reference back to TOS.

9 "Yesterday’s Enterprise"

'The Next Generation,' Season 3, Episode 15

The Enterprise-C was believed to have been destroyed 20 years prior in “Yesterday’s Enterprise,” only to emerge from a temporal anomaly and create an alternate timeline in which the Federation and Klingon Empire were at war, and the Federation was losing. Tasha Yar (Denise Crosby), who was killed in the first season, was alive and well. Only Guinan (Whoopi Goldberg) knew something was off, and she thought the only solution was to send the Enterprise-C back to its own time.

“Yesterday’s Enterprise” was a gritty episode of The Next Generation which explored time travel and alternate timelines. It was popular not only in Nielsen ratings in syndication, but many fans and TNG cast and crew alike, hail it as one of the series’ best. It also explored the theme of self-sacrifice and the greater good. As to put things right, the crew of the Enterprise-C had to accept and knowingly head towards their deaths.

8 "Darmok"

'The Next Generation,' Season 5, Episode 2

In “Darmok, the Enterprise comes across a civilization which communicates solely through metaphors. They had been contacted before but were deemed impossible to communicate with, and their language could not be deciphered by the crew’s universal translator. Picard struggles in his attempts to communicate with them after being captured and trapped on an alien planet with their captain, Dathon (Paul Winfield), where they were attacked by a monster with the ability to disappear and reappear.

“Darmok” was a profound episode of The Next Generation and a notable one for Picard in particular. It demonstrated his commitment to nonviolence and peace, as he continuously thought Dathon wanted to fight, and he refused, as well as his patience and willingness to learn, all qualities which proved he was a great captain. While Dathon’s ultimate death was tragic, it helps solidify “Darmok” as a moving episode about communication.

7 "Memento Mori"

'Strange New Worlds,' Season 1, Episode 4

The Enterprise went on a routine supply mission to a colony planet in “Memento Mori.” When they arrived, Spock (Ethan Peck) noticed the settlement’s communications satellite had been destroyed, leading Pike to send a landing party to investigate, who found no signs of human life but rather a gruesome scene with bloody drag marks but no bodies. The crew was ultimately attacked and forced to flee from the Gorn.

“Memento Mori” helped prove Strange New Worlds could be just as good as the classic, beloved Star Trek and is one of the standout episodes of the series, and it’s also among the best in the franchise. It was a compelling action-packed episode with a thrilling battle sequence and a cat-and-mouse game, and the Gorn proved to be a terrifying enemy. The episode also provided great insight into the characters of the Enterprise.

Star Trek: Strange New Worlds can be streamed on Paramount+ in the U.S.

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6 "The Measure of a Man"

'The Next Generation,' Season 2, Episode 9

At a newly established Starbase in “The Measure of a Man,” Data (Brent Spiner) was ordered to be transferred and serve under Captain Bruce Maddox (Brian Brophy), who wanted to disassemble and study Data in order to create replicas of him. Data refuses and resigns instead, triggering a debate over whether he was considered a person with all the rights that entailed or if he was considered Starfleet property, with Picard defending Data’s humanity.

The Next Generation often dealt with Data’s humanity, and the aptly titled “The Measure of a Man” tackled the issue head-on. The episode is often held up as the first great episode of TNG’s run. While it was a notable one for Data with a fantastic performance from Brent Spiner, Stewart also stood out, especially as Picard offered a passionate defense of Data. Picard and Maddox were also stark contrasts with one another, as Maddox never treated Data with any of the same respect he would a human.