(Note: stardates sometimes seem to be messed up somewhat, but i'm mentioning events in the order they're mentioned in Chronology. Where stardates are not given, none were mentioned in the episode. These episodes aren't all in the same order they're listed at startrek.com for some reason, either. Oh well. Anyway, I'll update some of these entries as I review their episodes every now and again.)
TOS Season One begins
Where No Man Has Gone Before (sd. 1312)
Kirk's old pal Gary Mitchell turns into a god and goes nuts. Kirk's forced to kill him.
The Corbomite Maneuver (sd. 1512)
Enterprise makes contact with First Federation ship Fesarius. Its commander, Balok, uses an unconvincing dummy to intimidate our heroes, but in the end they make friends with him and knock back a few tranyas together.
Mudd's Women (sd. 1329)
We meet Harcourt Fenton Mudd. Nothing of any great import transpires. Something about lithium crystals (yes, lithium), and women using a drug to make themselves beautiful. I dunno.
The Enemy Within (sd. 1672)
A transporter malfunction splits Kirk's good and evil sides into two separate people. The episode introduces the Vulcan nerve pinch. Kirk's two halves are eventually reintegrated.
The Man Trap (sd. 1513)
Folks are forced to kill a salt-sucking creature on planet M-113. Last of its species. So sad.
The Naked Time (sd. 1704)
Enterprise is assigned to pick up some scientists on planet Psi 2000. But, they're all dead. Landing party brings a virus back to the ship. The virus causes everyone (including Kevin Riley, who locks himself in Engineering, declares himself captain, and shuts down the engines, causing Enterprise's orbit to decay) loses control of their emotions. Even Spock! An emergency restart of the ship's engines using a theoretical intermix formula causes Enterprise to go back in time, like 71 hours.
Charlie X (sd. 1533)
The starship Antares delivered 17-year-old orphan Charles Evans to the Enterprise, who were to deliver him to Colony Alpha 5. He'd been living on Thasus pretty much forever, where the Thasians, who folks previously believed were mythical, gave him telekinetic powers. Charlie was pretty excited to be around his own kind for the first time, especially Yeoman Janice Rand. She was the first female he'd ever seen I guess, which is the only explanation I can think of for why he became so obsessed with her to the exclusion of all other women on Enterprise. Anyway, before long Charlie's powers caused all kinds of trouble. He destroyed the Antares and made people and phasers and stuff disappear, even made Spock recite poetry. This guy would've totally fit in with the Platonians. The episode very much reminds me of the Twilight Zone ep "It's a Good Life." Anyway, he eventually took over the ship, but then the Thasians took him back to Thasus so he couldn't cause any more trouble. They also brought back people Charlie had made vanish. Oh yeah, and Uhura sang some stuff in the rec lounge while Spock played his lyrette.
Balance of Terror (sd. 1709)
A Romulan ship with a cloaking device destroys some Federation outposts. The Enterprise destroys the Romulan ship.
What Are Little Girls Made Of? (sd. 2712)
On planet Exo III nurse Chapel visits her fiance, Dr. Roger Korby, who's used some old alien technology to make some androids, and put his mind into one. There's also a big scary ancient android called Ruk, aka "Lurch."
Dagger of the Mind (sd. 2715)
There's this penal colony on Tantalus V, more like an asylum, really. And there's this neural neutralizer and doctors going nuts and stuff. This episode introduces the Vulcan mind-meld.
Miri (sd. 2713)
Grups suck, onlies rule, 'nuff said. Oh yeah, and McCoy develops an antitoxin.
The Conscience of the King (sd. 2817)
An actor calling himself Anton Karidian is actually the infamous Kodos the Executioner, who um... made a little mistake 20 years ago. Only Jim Kirk and Kevin Riley would recognize him. Karidian's daughter Lenore kills a bunch of people and tries to kill Kirk and Riley, too. Nevermore! ...Um, and Uhura sang "Beyond Antares."
The Galileo Seven (sd. 2821)
Shuttlecraft Galileo is investigating Murasaki 312, when it crash lands on planet Taurus II. Then the shuttlecraft attains orbit briefly and Spock ignites their fuel in an attempt to signal Enterprise.
Court Martial (sd. 2947)
Kirk is accused of pushing buttons out of order, thus causing the death of Ben Finney. He's defended by Samuel T. Cogley, and prosecuted by one of his countless ex-flames, Areel Shaw. Spock realizes Finney must be alive because Spock keeps beating the computer at tri-D chess, or something.
The Menagerie, Parts I & II (sd. 3012-13)
Spock kidnaps Fleet Captain Christopher Pike, former captain of the Enterprise, and violates General Order 7 by commandeering the Enterprise and bringing it to Talos IV, where he'd been with Pike years ago. Pike stays on Talos, where the Talosians can give him the illusion of not being a charred lump in a Davros-chair with nothing but a blinking light to say "yes" or "no."
Shore Leave (sd. 3025)
All kinds of wacky things happen on an amusement park planet.
The Squire of Gothos (sd. 2124)
There's this stupid spoiled kid called Trelane who just happens to be from an extremely advanced civilization that can create planets, and he wants to play with some Earth people from the Enterprise.
Arena (sd. 3045)
A Federation colony on Cestus III has been destroyed by some Gorn. Enterprise pursues them, then some ancient and powerful Metron dude makes Kirk and the Gorn captain (a giant lizard who could whup Kirk's ass hands down) fight each other. Kirk makes a diamond cannon, though, beats him, spares his life, and finds out the Federation was unwittingly moving into Gorn territory, anyway.
The Alternative Factor (sd. 3087)
There's this guy Lazarus, and this other guy Lazarus, and one of them's from an antimatter universe, and they're doomed to fight each other forever. And oh yeah, their little conflict nearly destroys both universes.
Tomorrow Is Yesterday (sd. 3113)
Enterprise is thrown back in time to 1969, where they meet an Air Force pilot named John Christopher, who they have to send back in time to just before he spotted Enterprise because if they didn't he'd never have a kid who'd grow up to do something important. Then Enterprise returns to its own time.
Return of the Archons (sd. 3156)
On Beta III there's this computer called Landru who's running things, until Enterprise crew makes it self-destruct. Also there are these guys in hooded cloaks. And Landru had like destroyed the starship Archon like a hundred years ago.
A Taste of Armageddon (sd. 3192)
On Eminiar VII there's this war going on with neighboring planet Vendikar. Both sides let computers tell them which areas have been hit by simulated attacks, and everyone in such areas reports to these death chambers or whatever. Enterprise is declared hit, but our folks don't wanna play that game....
Space Seed (sd. 3141)
Enterprise finds the old sleeper ship S. S. Botany Bay on which Khan Noonien Singh and some other supermen from Earth's Eugenics Wars had escaped back in 1996. After being revived, they tried to take over the Enterprise, but were unsuccessful. Kirk sent them to start their own colony on Ceti Alpha V, and Enterprise crewmember Marla McGivers decided to go with them, rather than face court martial for helping them. I believe she married Khan.
This Side of Paradise (sd. 3417)
On Omicron Ceti III, these spores kept colonists alive despite exposure to lethal Berthold rays, but the spores also had some psychological effects which made everyone kind of... needin' to stick around forever and be all happy and stuff, even Spock. Then Kirk got his crew back and they left.
The Devil in the Dark (sd. 3196)
Miners on Janus VI got attacked by a Horta cuz they wuz unwittingly killing the eggs it was guarding. But in the end they all learned to work together.
Errand of Mercy (sd. 3198)
The Klingons, led by Commander Kor, and the Federation, led by Captain Kirk, both wanted planet Organia, and got into a fight over it, until the Organians turned out to be these superpowerful noncorporeal beings who stopped them from fighting and imposed the Organian Peace Treaty on them.
The City on the Edge of Forever
The Guardian of Forever is discovered and McCoy goes through it to 1930 Earth and saves Edith Keeler's life, thus ensuring the Federation would never exist or something. Kirk and Spock went through the Guardian to fix time and Kirk fell in love with Edith, then had to prevent McCoy from saving her. Thus the future was saved.
Operation: Annihilate! (sd. 3287)
Some extragalactic flying pancakes wiped out the populations of several planets, including the Deneva colony. Its victims included Kirk's brother, George Samuel Kirk, Jr., and his sister-in-law, Aurelan. They were survived by their son Peter. And McCoy figured out how to kill the flying pancakes.
TOS Season Two begins.
Catspaw (sd. 3018)
On planet Pyris VII, some aliens transmutate matter and stuff. I think they were from another galaxy or something.
Metamorphosis (sd. 3219)
On a planetoid in the Gamma Canaris region, Kirk, Spock, McCoy, and Commissioner Hedford meet Zefram Cochrane and this weird Companion thing. Hedford is terminally ill and decides to stay behind. Kirk promises not to tell anybody about Cochrane and the Companion.
Friday's Child (sd. 3497)
On Capella IV, the Enterprise is sent to negotiate a mining treaty, although Klingons also want mining rights, and there's also a local power struggle. Then a baby is born and gets named Leonard James Akaar, after McCoy and Kirk.
Who Mourns For Adonais? (sd. 3468)
Enterprise discovers this guy Apollo, one of a group of powerful aliens who played at being gods on Earth 5000 years ago. He falls for an anthropologist on the crew, who says she thinks of him as a specimen and nothing more. So he gets all upset and goes to join his fellow gods, wherever they went to.
Amok Time (sd. 3372)
Spock's going through pon farr and has to go to Vulcan where he's supposed to Marry T'Pring, who demands a Koon-ut-kal-if-fee challenge where Spock has to fight Kirk. McCoy gives Kirk something that makes it seem like Spock kills him. Then Spock is so sad it just shocks him right out of pon farr, I guess. So he leaves and T'Pring decides to marry this Stonn guy, cuz they're in love and Spock was just this arranged marriage neither of them really wanted anyway. Spock was pretty happy that Kirk turned out to be alive.
The Doomsday Machine
Commodore Matt Decker is the sole surviving member of the Constellation. There's this extragalactic planet-killing machine that has to be stopped before it eats again. So Decker takes the Constellation into the mouth of the beast and blows his ship up, which deactivates the planet killer. Doesn't scratch it or nuthin, though.
Wolf in the Fold (sd. 3614)
On Argelius II, Scotty is accused of murder. But it turned out to be the fault of an energy entity that feeds off fear. I think it was Jack the Ripper or something.
The Changeling (sd. 3451)
An old Earth probe called Nomad combined with an alien probe called Tan Ru and their programming got merged. Nomad was all, "Hey, you got soil sterilizing in my extraterrestrial life seeking," and Tan Ru was like, "No, you got extraterrestrial life seeking in my soil sterilizing!" Then they were all, "Hey... let's sterilize all life-forms!" Luckily, Nomad thought Kirk was Jackson Roykirk, its father, so he was able to use some parental psychology to make Nomad kill itself. Oh yeah, and Nomad killed some folks and brought them back to life and stuff.
Around this time, Ceti Alpha VI explodes and disrupts the orbit of Ceti Alpha V, resulting in catastrophic climatic changes which devastate Khan's colony. Aside from Khan and most of his followers, the only surviving organism is the Ceti Alpha eel.
The Apple (sd. 3715)
On Gamma Trianguli VI, a computer called Vaal kept the human civilization stagnant, and no one ever had sex, so the folks from Enterprise destroyed Vaal and left the Triangulans to figure things out.
Some folks from Enterprise were switched in another transporter malfunction with their counterparts from the mirror universe, where everyone was all evil and stuff, and instead of the United Federation of Planets, there was a Terran Empire. Spock was less evil because of logic I guess, but he still looked more satanic with that goatee or whatever. Anyway, everyone switched back to their proper universe in the end. And later on Spock turned the Empire good or something, leaving the way open for its eventual fall.... But that's another story....
The Deadly Years (sd. 3478)
On Gamma Hydra IV, some disease hyperaccelerated everyone's aging. McCoy develops a cure.
I, Mudd (sd. 4513)
Mudd is on a planet full of androids from the Andromeda galaxy whose sun had gone nova. They tried to take over Enterprise. They failed.
The Trouble with Tribbles (sd. 4523)
On Deep Space Station K-7, there was this quadrotriticale stuff (a special hybrid wheat) that was needed on Sherman's Planet, which had been claimed by the Federation as well as the Klingon Empire. A Klingon poisoned the quadwhatever, which was discovered because the Tribbles ate it and died. Um, yeah, there was this guy Cyrano Jones, who was selling Tribbles, which muliplied faster than Mogwai in water. And they were all cute and stuff, but they hate Klingons, and the feeling is mutual. And a Tribble discovered that some guy was actually a disguised Klingon. Later Scotty beamed all the Tribbles over to the Klingon ship. And um, Captain Koloth was in this episode.
Bread and Circuses (sd. 4040)
On planet 892-IV, there's a kind of Roman civilization going on, with a kind of Christian religion just starting to develop. A landing party is captured and then rescued.
Journey to Babel (sd. 3842)
Enterprise is transporting some dignitaries to Babel for talks about whether to admit Coridan to the Federation. Among the dignitaries are Spock's parents, Sarek of Vulcan and Amanda Grayson of Earth. Sarek was accused of murdering a Tellarite or something. Also Sarek had a heart attack. But everything turned out alright in the end, and it was all Orion's fault or something. Spock and Sarek exchanged a bit of staid humor about Amanda.
A Private Little War (sd. 4211)
On some planet the Klingons were giving these primitive people advanced weapons, which forced the Federation to give these other primitive people advanced weapons. Dr. M'Benga was in this episode, which also featured a mugato (like the Abominable from that Rudolph cartoon, only closer to man-size).
The Gamesters of Triskelion (sd. 3211)
Some brains encased in glass capture folks to use as thralls in athletic competitions for the brains' amusement. Kirk puts a stop to that nonsense.
Obsession (sd. 3619)
Kirk is obsessed with a vampiric cloud that's killing his Enterprise crewmembers just like it killed people on the Farragut 11 years ago. He pursues it to Tycho IV and kills it.
The Immunity Syndrome (sd. 4307)
A giant space amoeba destroys the Intrepid and kills billions of people in the Gamma 7A system. So Enterprise destoys it.
A Piece of the Action
A century ago some idiot from the Horizon left a book on Sigma Iotia II, and the inhabitants went and remodeled their whole society after the book, which was like about 1920s Chicago gangsters or something. So Enterprise had to do their best to clean that mess up, but there wasn't much they could do. Plus some idiot from Enterprise left a communicator behind when they left.
By Any Other Name (sd. 4657)
Agents of the Kelvan Empire, from the Andromeda galaxy, want to establish a colony in our galaxy. Those silly Kelvans thought they'd have to invade us, but Kirk told them they could have a planet without fighting us. A messenger drone was sent back to the Empire to inform them of this.
Return to Tomorrow (sd. 4768)
There was this war half a million years ago that destroyed a whole race and now there were just a few of them left as consciousnesses in canisters. We tried to give them android bodies, but this guy Henoch tried to steal a living body and he had to be destroyed. Then these other two folks, Sargon and Thalassa departed into oblivion.
Patterns of Force
This idiot named John Gill, who was stationed on Ekos, imposed a Nazi government and was surprised when it turned evil.
The Ultimate Computer (sd. 4729)
Dr. Richard Daystrom was testing his M-5 multitronic computer. It destroyed the Excalibur and stuff, so Kirk and this guy Commodore Wesley had to disconnect it.
The Omega Glory
On planet Omega IV, there was some kind of bacterialogic warfare probably at least 1000 years ago and anyone who went there and then left died, like the crew of the Exeter, but the planet produced some kind of immunity stuff, so anyone who stayed there would be okay I guess.
Enterprise goes back to 1968 and meets Gary Seven who had a cat and a secretary and a nifty computer and stuff, and they all made sure Earth never blew itself up and stuff.
TOS Season Three begins.
Spectre of the Gun (sd. 4385)
On Melkot, the Melkotians make some unreal stuff happen and there's a gunfight at the OK Corral and stuff.... Spock makes sure everybody knows it isn't real so bullets can't hurt them. Then the Melkotians agree to diplomatic relations with the Federation.
Elaan of Troyius (sd. 4372)
Enterprise was transporting Elaan from Elas to Troyius to end a war. Also Klingons wanted some dilithium on Troyius. And there was this whole thing about Elasian tears being aphrodisiacs....
The Paradise Syndrome (sd. 4842)
On an away mission, Kirk gets lost and loses his memory and marries a native woman named Miramanee. And I think like the Preservers or somebody moved these natives here from Earth a long time ago. Their ancestors I mean. And Miramanee gets killed and Kirk gets his memory back and goes home.
The Enterprise Incident (sd. 5027)
Enterprise crosses the Neutral Zone and is captured by Romulans. The Romulan commander has a thing for Spock it seems. Meanwhile Spock and Kirk are just on a mission to steal the cloaking device. They also captured the Romulan commander.
And the Children Shall Lead (sd. 5029)
A noncorporeal guy called the Gorgan was using kids to do his dirty work, but the folks from Enterprise eventually set them straight and Gorgan left or whatever.
Spock's Brain (sd. 5431)
I prefer to consider this episode apocryphal. Some babes from Sigma Draconius VI, who were controlled by a computer, stole Spock's brain and later McCoy put it back in Spock's head.
Is There in Truth No Beauty? (sd. 5630)
There's this Medusan ambassador named Kollos, and if you look at a Medusan you go nuts, which happens to this guy Marvick, who pilots Enterprise past the energy barrier at the edge of the galaxy. There's also this woman, Dr. Miranda Jones, who I guess spent some time on Vulcan and had this IDIC pin or whatever. She mind-melded with Kollos, okay? Or something like that.
The Empath (sd. 5121)
There were like some aliens called Vians I guess, and a mute woman named Gem, and um, a bizarre experiment, and it was all kind of ridiculous, really.
The Tholian Web (sd. 5693)
Investigating the disappearance of the Defiant (not the DS9 ship, obviously), Enterprise gets caught in a Tholian web while Kirk disappears in an interphase of two universes or something. But everything works out in the end.
For the World Is Hollow and I Have Touched the Sky (sd. 5476)
There's this asteroid ship called Yonada which is going to crash into Daran V and kill a bunch of folks there. It had left the Fabrina system like 10,000 years ago when their sun went nova and now nobody on board knew the truth about Yonada or anything, and the computer was busted and stuff. But the Enterprise folks manage to fix Yonada up and set it back on its proper course and also find a cure for some disease McCoy had.
Day of the Dove
In this episode, we meet Klingon commander Kang. A silly ball of light feeds on hatred and forces Klingons and the Enterprise crew to fight each other until we figure out its game and stand around laughing at it and slapping each other on the back.
Plato's Stepchildren (sd. 5784)
A long time ago these folks from the Sahndara system left home when their sun went nova, and then spent some time on Earth studying with Plato, then went to this other planet they called Platonius, where the food had this drug called kironide in it that gave them telekinetic powers. So now they used the Enteprise crew as playthings, until McCoy synthesized the drug and injected it into the crew's systems so they could fight back. This guy Alexander left with Enterprise, and I think later he went back to the 1870's to pester James West and Artemus Gordon.
Jax would later use kironide against changelings in Mirror Gamma.
Wink of an Eye (sd. 5710)
These people on Scalos had been hyperaccelerated but were genetically damaged and wanted the Enterprise crew for breeding stock, but they didn't get their wish I guess, cuz we're all still slow.
That Which Survives
This old computer image woman Losira was protecting this Kalandan colony even though everyone there had been dead for a long time. She gave Enteprise some trouble, but everything turned out all right.
Let That Be Your Last Battlefield (sd. 5730)
This guy Lokai from planet Cheron was being chased by this guy Bele because one's face was black on the left and white on the right, while the other's face was white on the left and black on the right. And because of this difference the whole population of Cheron killed each other.
Whom Gods Destroy (sd. 5718)
There's this penal colony on Elba II. Again, more like an asylum. Former captain Garth of Izar took the place over with some other inmates and captured Kirk and Spock, but they eventually set things right down there.
The Mark of Gideon (sd. 5423)
Planet Gideon had way too many people and got disease organisms from Kirk's blood so folks could start dying and decrease the surpluss population.
The Lights of Zetar (sd. 5725)
Enterprise is taking Lt. Mira Romaine to Memory Alpha, where Federation history and scientific knowledge is archived. Some energy phenomenon shows up and attacks Memory Alpha and kills everyone and stuff. They tried to take over Romaine's body, but the Enterprise folks expell them. Um, and I think she had a little romance with Scotty.
The Cloud Minders (sd. 5818)
We need to get some zenite from planet Ardana. There's this clash between the folks who live in the clouds and the folks who live in the mines, but everything works out in the end.
The Way to Eden (sd. 5832)
A Tiburonian scientist named Dr. Sevrin is leading some hippies on a quest to find a mythical planet they think is Eden. They got there and the environment was toxic. But Spock played his lyrette with the hippies, because he reached, man! He is so not Herbert.... You just can't help but grok a guy like that, can ya?
Requiem for Methuselah (sd. 5843)
This guy Flint on planet Holberg 917G turned out to be this ancient dude from Mesopotamia who had been a whole bunch of famous people throughout the ages. But he was dying because he had left Earth. Anyway, Enteprise was there to get some ryetalyn to cure an outbreak of Rigelian fever. Um, and Flint had created this android named Rayna Kapec who he hoped would fall in love with Kirk so that she'd understand love, so she could fall in love with Flint. But she thought of Flint as a father and loved both men and died because she couldn't stand them fighting over her. Then later Spock did this Vulcan "forget" thing to make Kirk forget he loved her.
The Savage Curtain (sd. 5906)
In which the Enterprise folks have to join with images of historical figures against images of other historical figures. There was Abraham Lincoln and Colonel Green and Surak and Kahless and some others I think. Then this Excalbian told everybody what was going on. Just some game so the Excalbians could learn about good and evil.
All Our Yesterdays (sd. 5943)
Planet Sarpeidon's star was about to go nova, so of course Enterprise wanted to help out. But everybody except librarian Mr. Atoz had already gone into the planet's past using the atavachron. Kirk, Spock, and McCoy also went into the past, and Spock reverted to the state of his pre-logic ancestors, and had a fling with this woman Zarabeth. Eventually everybody got back to the present, and Atoz went into the past, and Enterprise left.
Turnabout Intruder (sd. 5928)
Dr. Janice Lester takes over Kirk's body because Starfleet was going through a sexist period wherein they didn't allow women to command starships (and also because she was insane). But everyone pretty well figured it wasn't really Jim Kirk in there, and turned against her, and got things set back to normal.
TOS Season Three ended.
Stuff in darkred text has to do with the series "Enterprise," which may or may not be accepted as officially part of the Star Trek universe.
Stuff in black text can generally be assumed to be part of official Star Trek, usually if not always taken from the Chronology (Michael and Denise Okuda), startrek.com, or the various shows and movies.