Star Trek gave us six TV series, spanning over 700 episodes, because it's such a rich universe. And a Federation starship is the perfect vehicle to tell unforgettable stories. But which Star Trek stories are the best? To find out, we painstakingly compiled the 100 greatest Trek episodes, from any of the series.
What makes for a great Star Trek episode? Obviously, the fun quotient has to be high, and there need to be awesome character moments. But I'd argue that a really notable Trek story explores some ideas, or some ethical quandaries, in a way that sticks with you after you're done watching. If one thing has defined Trek throughout its run, it's that.
So here's our list of the 100 best Star Trek episodes. Please let us know which episodes we missed, or ranked incorrectly!
Warning: some spoilers below, although we try not to give away all the plot twists.
100) Bride of Chaotica! (Star Trek: Voyager) - A hilarious pastiche of old-school science fiction serials, this story puts the Voyager crew in the middle of a space-opera fantasy gone very, very wrong.
99) Day of the Dove (Star Trek) - An alien entity wants the Enterprise crew and some Klingons to slaughter each other, and Kirk has nearly as much trouble with his own crew as with the "enemy."
98) Paradise (Star Trek: Deep Space Nine) - Sisko and O'Brien find themselves in a "perfect" society where no technology functions, and the society's matriarch tests Sisko's will with some pretty brutal treatment.
97) Borderland/Cold Station 12/The Augments (Enterprise) - In this three-part episode, we delve into the past of Khan Noonien Singh's genetically augmented crew, and also meet the ancestor of Data's creator. And connecting those two dots allows the story to get into some weird questions about the nature of "superior" people.
96) Lineage (Star Trek: Voyager) - B'Elanna and Tom are expecting a baby... but maybe they can genetically engineer it to be more human and less Klingon? More than any episode about Khan's people, this episode digs into the thorny ethics of eugenics.
95) The Most Toys (Star Trek: The Next Generation) - Data is taken prisoner by an unscrupulous collector, and the android finds out just how far he's willing to go to win his freedom.
94) Disaster (Star Trek: The Next Generation) - A calamity cuts off the different sections of the ship from each other, leaving Deanna Troi in charge, and Worf having to deliver a baby.
93) Future's End (Star Trek: Voyager) - An evil Bill Gates-type in the 1990s has gotten hold of a 29th century ship, and even the Voyager crew might not be able to keep him from changing history.
92) The Magnificent Ferengi (Star Trek: Deep Space Nine) - Of all DS9's "Ferengi comedy" episodes, this is one of the funniest — Quark has to rescue his mother from the Dominion, but everything goes absolutely pear-shaped and Quark has to improvise.
91) The Killing Game (Star Trek: Voyager) - The Hirogen love to hunt, so what could be better than turning Voyager into a recreation of World War II? (Lots of things. But that's what they do, anyway.)
90) Booby Trap (Star Trek: The Next Generation) - The Enterprise is trapped in a weird space trap, and Geordi can't find a solution until he makes himself a new colleague... who's the woman of Geordi's dreams.
89) Court Martial (Star Trek) - Kirk is put on trial, and along the way he shows what it really takes to command a starship.
88) Favor the Bold/Sacrifice of Angels (Star Trek: Deep Space Nine) - This episode is a turning point in the "Dominion War" arc. But more to the point, it features a ginormous, amazing space battle, featuring hundreds of starships.
87) Déjà Q (Star Trek: The Next Generation) - Q has lost his powers, and now he's learning to cope with being human. If he can survive the wrath of Guinan, that is.
86) Memorial (Star Trek: Voyager) - Voyager was at its best when coping with strange thought experiments, and here's a doozy: a memorial forces you to experience a terrible war first-hand. Should it be allowed to remain operational?
85) Little Green Men (Star Trek: Deep Space Nine) - Quark gets stranded on mid-20th century Earth, and for once even he can't figure out how to profit from this, in a hilariously weird episode.
84) Parallels (Star Trek: The Next Generation) - Worf keeps jumping to various (and highly entertaining) alternate realities, showing how different his life could be with just a few changes.
83) Timeless (Star Trek: Voyager) - One of the many "alternate future crewmembers averting a past tragedy" storylines, this one features the beautiful image of Voyager crashed into an ice planet, and Chakotay going to extremes to save his friends.
82) Conundrum (Star Trek: The Next Generation) - The entire crew of the Enterprise suffers memory loss, but luckily First Officer MacDuff is here to help. When their identities are stripped away, will the Starfleet officers still do the right thing?
81) The Enemy Within (Star Trek) - The one where Kirk gets split into good and evil versions by a transporter accident — Richard Matheson's script manages to get into some thorny questions about the nature of evil.
80) The Wounded (Star Trek: The Next Generation) - The Federation is trying really hard to have peace with the Cardassians, but some people in Starfleet aren't quite so ready to forgive and forget... and it's up to Picard to help out his enemies.
79) I, Mudd (Star Trek) - The most famous rogue in Star Trek has landed in a great spot — surrounded by beautiful androids who cater to his every whim. Except that he can't leave.
78) Remember Me (Star Trek: The Next Generation) - Dr. Crusher is faced with a mystery that gets at her fear of abandonment, but also questions of existence, when people start vanishing around her.
77) Our Man Bashir (Star Trek: Deep Space Nine) - The goofiest of DS9 episodes (well, one of the goofiest) sees Bashir stuck in a holosuite program where he's a James Bond-style spy.
76) Wolf in the Fold (Star Trek) - Mr. Scott is accused of being a serial killer... but the truth is a lot more bizarre.
75) The Raven (Star Trek: Voyager) - One of the best "Seven of Nine tries to become more human" episodes actually sees her coping with her memories of being part of the Borg.
74) Living Witness (Star Trek: Voyager) - Hundreds of years after Voyager visit a planet, its crew are remembered as war criminals, as shown in a historical reenactment.
73) Family (Star Trek: The Next Generation) - This episode is revolutionary, purely because it shows the consequences of a big "event" episode — Picard is still shaken by his experiences with the Borg, when he goes home to visit his family.
72) Who Mourns For Morn (Star Trek: Deep Space Nine) - The barfly who hangs out in Quark's bar has apparently died, but will Quark really inherit all his worldly goods?
71) A Piece of the Action (Star Trek) - One of many "visiting Earth's past on another planet" episodes, this is the funniest and also the most trenchant. Kirk and friends have to outwit a whole planet of gangsters, while teaching them the arcane game of Fizzbin.
70) Sarek (Star Trek: The Next Generation) - Peter S. Beagle wrote this episode where Spock's father reappears, and he's not the Vulcan he used to be — a bittersweet exploration of aging and loss.
69) What You Leave Behind (Star Trek: Deep Space Nine) - The DS9 finale packs a lot of punches, including the final showdown with the Dominion, and Sisko embracing his destiny.
68) Tin Man (Star Trek: The Next Generation) - a powerful Betazoid telepath is obsessed with a giant sentient spaceship, but also develops a friendship with Data, the only person whose thoughts he can't read.
67) Errand of Mercy (Star Trek) - The first Klingon episode is also the most daring, as Kirk is portrayed as being nearly as warlike as his foes, in the face of godlike pacifist aliens.
66) Dark Frontier (Star Trek: Voyager) - Seven of Nine starts to remember her past before she became a Borg drone, as Janeway schemes to steal from the Borg.
65) In Purgatory's Shadow/By Inferno's Light (Star Trek: Deep Space Nine) - One of the most shocking of the "Dominion War" storylines, this two-parter reveals a terrible secret about Bashir, and changes the balance of power in the Alpha Quadrant.
64) The Slaver Weapon (Star Trek: The Animated Series) - Written by Larry Niven, this episode sees the Enterprise crew meeting the Kzinti... and dealing with a self-aware ultimate weapon.
63) Assignment: Earth (Star Trek) - Kirk and Spock go back to the 1960s, but they're not the only interloper. This was the "backdoor pilot" for a spin-off show that never happened, but it's still bizarrely entertaining in its own right.
62) Cause and Effect (Star Trek: The Next Generation) - The one where the Enterprise keeps blowing up over and over. The most explosive, bewildering time loop ever.
61) Course: Oblivion (Star Trek: Voyager) - These alternate versions of a starship crew aren't evil — just very, very fragile. This is one of those episodes whose nihilism makes it almost like a weird dream.
60) Shore Leave (Star Trek) - One of the goofiest original-series episodes also has a major dark side, as the crew arrives on a planet where anything they imagine can become real. Anything.
59) The Quickening (Star Trek: Deep Space Nine) - Dr. Bashir's miracle-worker image faces an extra challenge when he faces a genetically-engineered plague.
58) Dagger of the Mind (Star Trek) - In the Federation's utopian future, the rehabilitation of criminals is much more humane. Much, much more humane. The psychological cruelty in this one is actually pretty intense.
57) The Sound of Her Voice (Star Trek: Deep Space Nine) - Everybody falls in love with a stranded Starfleet captain who's sent out a distress call. But can she be saved?
56) Tuvix (Star Trek: Voyager) - The Voyager crew face another huge ethical conundrum... and arguably, this time they choose wrong.
55) The Pegasus (Star Trek: The Next Generation) - Riker's long-buried secret comes to light, and he's forced to lie to Captain Picard.
54) Caretaker (Star Trek: Voyager) - Greg Cox argued (in our comments) this is the best first episode of any Trek, and he has a point: it shows Captain Janeway making two tough choices: stranding her crew, and adopting a crew of rebels.
53) The Conscience of the King (Star Trek) - This episode about a Shakespearean actor who may be a legendary mass murderer is also our first glimpse of the flaws in Trek's perfect future.
52) Relics (Star Trek: The Next Generation) - Old Starfleet engineers never die — they just come back decades later, eager to tinker with another warp engine.
51) Necessary Evil (Star Trek: Deep Space Nine) - The best of the episodes about the shapeshifting Odo doing detective work, because his digging turns out to reveal some dark secrets.
50) I Borg (Star Trek: The Next Generation) - Another episode with a guest star who poses a huge ethical question — the Enterprise finds a disconnected Borg drone, and tries to turn him into a weapon.
49) The Wire (Star Trek: Deep Space Nine) - The mysterious Garak finally has to reveal a little bit about his past to his friend Dr. Bashir, to save his life — but which stories are lies, and which ones are true? Or is there really any difference?
48) The Enterprise Incident (Star Trek) - Kirk and Spock pull an elaborate hustle on the Romulans, in an episode that shows just how unethical our heroes are prepared to be.
47) Perfect Mate (Star Trek: The Next Generation) - Picard falls for a woman (Famke Janssen!) who is destined to marry a warlord in an arranged marriage, and he has to put his feelings aside for the sake of peace.
46) Blink of an Eye (Star Trek: Voyager) - In yet another high-concept Voyager outing, the starship appears in the sky over a planet for a relatively brief time, but that's long enough for it to loom over the life and death of an entire civilization.
45) Dear Doctor (Enterprise) - Doctor Phlox relates his experience dealing with a plague affecting a relatively primitive planet, which turns out to pose an impossible dilemma.
44) It's Only a Paper Moon (Star Trek: Deep Space Nine) - Like "Family," this is an episode that takes a hard look at the process of recovering from trauma... and doesn't sugar-coat the truth.
43) Obsession (Star Trek) - Kirk's judgment is called into question when he becomes fixated on revenge, showing once again just how dangerous an out-of-control captain can be.
42) Hard Time (Star Trek: Deep Space Nine) - The best of the many "Let's torture O'Brien" episodes, in which he receives false memories of 20 years of imprisonment.
41) Rocks and Shoals (Star Trek: Deep Space Nine) - Sisko's crew are stranded on a planet with some of the enemy Jem'Hadar... and the Jem'Hadar's unquestioning drug-induced loyalty is put to the test, horribly.
40) In A Mirror Darkly, Parts 1 & 2 (Enterprise) - The best of the "Mirror Universe" sequels, this episode shows us a more unscrupulous version of Jonathan Archer... who's just inherited a Federation ship from the future.
39) Journey to Babel (Star Trek) - Most notable for introducing us to Spock's parents, this episode also shows a Federation diplomatic mission gone horribly wrong.
38) The Way of the Warrior (Star Trek: Deep Space Nine) - With the Federation facing war with the Dominion, it's a good thing the Klingons are here to help. Except sometimes your allies can be more dangerous than your enemies.
37) Lower Decks (Star Trek: The Next Generation) - This episode follows four junior officers aboard the Enterprise, and lets us see the command staff through the eyes of their underlings.
36) Galileo Seven (Star Trek) - A shuttlecraft full of people is stranded on a planet, and it appears that not all of them can survive. Good thing Spock is in charge, and he has zero hesitation about making the tough call... Right?
35) Inter Arma Silent Leges (Star Trek: Deep Space Nine) - Bashir has always wanted to play at being a spy... so how does he like doing it in real life? One of the episodes that exposes the terrible underbelly of the Federation.
34) The Drumhead (Star Trek: The Next Generation) - An Admiral subjects the Enterprise to an inquisition, and starts finding conspiracies behind every bulkhead, providing an object lesson in the dangers of paranoia.
33) Twilight (Enterprise) - In the future, Archer has dementia, and the human race has lost a devastating war. And both things are equally terrible to behold.
32) Trials and Tribble-ations (Star Trek: Deep Space Nine) - One of several time-travel episodes, this one sends Sisko's officers back to the original series episode "The Trouble With Tribbles," and provides a great love letter to Trek's history.
31) Call to Arms (Star Trek: Deep Space Nine) - This is the one where Sisko makes the tough choices, and a highly symbolic baseball is the only hint of Sisko's endgame.
30) Yesteryear (Star Trek: The Animated Series) - Spock travels back in time and saves himself as a young boy on Vulcan, in an episode that reveals a lot about Spock's life.
29) The Void (Star Trek: Voyager) - When Voyager gets trapped in a pocket space with a bunch of other ships that prey on each other, Janeway has to convince everybody to work together to escape. Janeway's finest hour.
28) Homefront/Paradise Lost (Star Trek: Deep Space Nine) - Nowadays, everybody trots out the "security versus freedom" question, but DS9 asked it first, and best, with this story of paranoia about shapeshifters in Starfleet.
27) Where No Man Has Gone Before (Star Trek) - The second Star Trek pilot is the best, facing Kirk with an impossible choice: condemn his friend to death, or risk his entire ship.
26) The Year of Hell Parts 1 &2 (Star Trek: Voyager) - The luckiest ship in the Delta Quadrant finally has really, really bad luck.
25) The Offspring (Star Trek: The Next Generation) - Data creates an android daughter for himself, but some miracles are too great to last.
24) Duet (Star Trek: Deep Space Nine) - Kira suspects that a visiting Cardassian is actually a notorious war criminal, and she's willing to go to insane lengths to prove it.
23) The Equinox (Star Trek: Voyager) - Captain Janeway's determination to uphold Federation principles far from home looks a lot more impressive when you meet another Starfleet crew that compromised, really badly.
22) Tapestry (Star Trek: The Next Generation) - Picard is dying of an old wound caused by his recklessness, so Q shows him what his life would be like if he'd played it safe.
21) Arena (Star Trek) - Kirk faces two impossible challenges: making a weapon from scratch, and upholding his values in the face of a murderous Gorn.
20) Measure of a Man (Star Trek: The Next Generation) - Putting Data on "trial" to see if he's a person raises fascinating questions, but the best part is Riker's total ruthlessness as prosecutor.
19) Yesterday's Enterprise (Star Trek: The Next Generation) - The Enterprise finds itself in an alternate universe, and restoring the original timeline will come at a high cost.
18) The Doomsday Machine (Star Trek) - Kirk faces the ultimate weapon, but his real nightmare is an unhinged superior officer taking command of the Enterprise.
17) The Siege of AR-558 (Star Trek: Deep Space Nine) - Lots of DS9 episodes explored the notion that war is Hell, but this one made it visceral and unforgettable.
16) Devil in the Dark (Star Trek) - The classic Star Trek scenario: a story in which the "monster" is misunderstood, and ignorant humans are the real danger.
15) Space Seed (Star Trek) - The only Trek episode to get a movie sequel, this story introduces a suave former dictator who's a perfect foil for Kirk.
14) The Corbomite Maneuver (Star Trek) - This episode isn't named after the villain or the McGuffin, but after Kirk's cunning gambit — with good reason. Never play poker with Kirk.
13) Far Beyond The Stars (Star Trek: Deep Space Nine) - Sisko hallucinates he's a pulp science fiction author writing about the impossible: a black captain named Ben Sisko.
12) Amok Time (Star Trek) - Our first visit to Spock's homeworld also shows how friendship and cunning are more powerful than mating rituals and ancient traditions.
11) Chain of Command (Star Trek: The Next Generation) - Picard is captured by a ruthless Cardassian torturer — and gets pushed to his limits.
10) Mirror, Mirror (Star Trek) - Meeting alternate crewmembers, including Bearded Spock, is cool — but the fascinating part is seeing our heroes try to pretend to be barbarians.
9) All Good Things (Star Trek: The Next Generation) - The best Q story sees Picard tested at three points in his life, with the whole universe in the balance.
8) The Inner Light (Star Trek: The Next Generation) - Picard lives a whole life on a doomed planet, and becomes a living memorial, with just a flute as souvenir.
7) In the Pale Moonlight (Star Trek: Deep Space Nine) - How far will Sisko go to get the Romulans to join the war? All the way.
6) The Trouble with Tribbles (Star Trek) - The funniest Trek, it also faces Kirk with the most insidious threat: an organism that's born pregnant.
5) Darmok (Star Trek: The Next Generation) - Quibble about the alien language all you want, this parable of learning to communicate remains powerful.
4) The Visitor (Star Trek: Deep Space Nine) - Jake Sisko has grown old as a famous writer, but he's willing to give it all up to save his father in the past. Absolutely beautiful.
3) City on the Edge of Forever (Star Trek) - Kirk, Spock and McCoy visit the 1930s, and Kirk faces an impossible choice that proves time travel is heart-breaking.
2) The Best of Both Worlds (Star Trek: The Next Generation) - The Borg turn Picard into their mouthpiece, and our heroes nearly lose.
1) Balance of Terror (Star Trek) - Kirk's battle of wits with a Romulan is spellbinding, but so is the exploration of prejudice, and the idea that noble people fight on both sides.
Portions of this list originally appeared in a "top 10" list back in 2011. Thanks to everybody who suggested stuff for this list over at the Observation Deck, especially Pessimippopotamus, Dr Emilio Lizardo, Erodgenator, JurassicBark, omgwtflolbbqbye, Gilese, Ghost in the Machine, Quasi Hatrack, KeithA0000, LizTaylorsEarrings, MasterChef_117, Kegg, Robert James, Poet Desmond, Erinaceus, Onelittledetail, Pie 'oh' Pah, Fauxcused, Terror and Love, Buck-Bokai, McGiggins, cohentheboybarian, Maveritchell, hyattch, Mudbud, sbtblab, Siete Ocho, Eesti, WiessCrack, Steven Lyle Jordan, tsalonich, llaalleell, KKGrotto, KiraNerys42,owensa42, Indiebear, tetanusRacing, Max Hansen, Kevin Bradley and everybody else who contributed. Thanks!