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''Star Trek: The Animated Series'' is an AnimatedAdaptation and the first SpinOff from [[Series/StarTrekTheOriginalSeries the original series]], continuing the initial five-year mission.

Given the reality that it was produced by Creator/{{Filmation}}, the animation is typically the studio's ultra-cheap style. However, they more than made up for that with most of the original cast and the writers as well. The result is a show that might not have the best animation, but still boasts spectacular imagery and believably non-human aliens that the original show could never depict, while still reasonably keeping to its artistic spirit. As a result, this series is the best example of the AnimatedAdaptation concept in UsefulNotes/TheDarkAgeOfAnimation, and was so good that it won the franchise's first ever Emmy Award.

''The Animated Series'' remains the shortest-lived series of the ''Franchise/StarTrek'' franchise, with just 22 episodes airing over a 13-month period in 1973-74 on Creator/{{NBC}}. It was also the last ''Trek'' series to air in first-run on network television until ''Series/StarTrekVoyager'' debuted in 1995 on Creator/{{UPN}}.

However, the franchise creator, Creator/GeneRoddenberry, later insisted that the animated show be kept out of continuity since he never anticipated that ''Star Trek'' would later be revived in live action on such a scale as would happen, with the film series and ''[[Series/StarTrekTheNextGeneration The Next Generation]]''. Still, many fans insisted that at least the best episode, "[[Recap/StarTrekTheAnimatedSeriesS1E2Yesteryear Yesteryear]]", be counted, considering that it gives a valuable look into Spock's youth and character as well as the planet Vulcan, as told by the most authoritative voice on the matter, D.C. Fontana. Because of the information about Vulcan presented in the show, as well as the introduction of the Holodeck and Kirk's middle name, and the fact that many of the ''Star Trek'' writers and actors were involved with the production, many fans consider it a part of their personal ''Star Trek'' {{canon}}, depicting the final two years of ''Enterprise's'' five year mission. In addition, the producers of ''Series/StarTrekEnterprise'' used numerous references from this series. The Franchise/StarTrekExpandedUniverse, already having less of a need to adhere to strict canon, even went so far as to revive the series' SixthRanger alien crew members, CatGirl Lt. M'Ress and [[MultiArmedAndDangerous tri-symmetrical Lt. Arex]].

Creator/{{CBS}} declared this series full canon around the time they released it on DVD.

The title used here and on the DVD release is a back-formation, as the show originally aired as simply ''Star Trek''. It's also known by the more ponderous title of ''[[LongTitle The Animated Adventures of Gene Roddenberry's Star Trek]]''.
!! This series provides examples of:
* AbsenteeActor: Everyone ''except'' Spock, Sulu, and Uhura in "The Slaver Weapon". Chekov is absent the whole series.
* AIIsACrapShoot: The planetary computer in "[[Recap/StarTrekTheAnimatedSeriesS1E9OnceUponAPlanet Once Upon a Planet]]", as a result of the Caretaker's death in the time since the Original Series episode "[[Recap/StarTrekS1E15ShoreLeave Shore Leave]]". It creates things like the Queen of Hearts and dangerous animals when nobody is thinking about them, and it captures Uhura.
* AlternateUniverse: "The Magicks of Megas-Tu" has a world in which practicing magic is the norm and "The Counter-Clock Incident" has a universe in which everything works backwards, including aging.
* AncientAstronauts: Kukulcan in "How Sharper than a Serpent's Tooth". He visited Earth in the distant past and was the basis for the Mayan god of the same name, the Toltec god Quetzalcoatl, and the Chinese dragons.
* AnimatedAdaptation: The best example thereof in the 1970s.
* ApocalypticLog: "Beyond the Farthest Star". The dead ship's log entry/warning.
* ArtificialGravity:
** The Enterprise's computer shuts off the gravity in "The Practical Joker."
** The fortress in "The Jihad" loses its gravity when the questers try to get at the MacGuffin in its center.
* AscendedMeme: "Beam me up, Scotty!" is famous for [[BeamMeUpScotty never being actually spoken]] in the Original Series, but it appears in this one.
* AssInAmbassador: The title character in "Bem". He swaps out Kirk's and Spock's communicators and phasers for counterfeits, runs off from the away team, doesn't even bother separating himself to escape when he is first captured, and leaves Kirk and Spock in their wooden cages when he does manage to escape.
* AsteroidThicket: In "[[Recap/StarTrekTheAnimatedSeriesS2E1ThePiratesOfOrion The Pirates of Orion]]", the ''Enterprise'' pursues the Orion ship into one.
* BarefootCartoonAnimal: Lt. M'Ress, who wears a full Starfleet uniform, except for footwear. {{Justified}} because she has digigrade paws (meaning she walks on her toes).
%%* BigDumbObject: "Beyond The Farthest Star"
%%* BigRedButton: "Beyond The Farthest Star". The auxiliary warp drive controls.
* {{Bowdlerise}}: By [[GermanTVStations German TV station ZDF]].
* BriarPatching: In "[[Recap/StarTrekTheAnimatedSeriesS2E3ThePracticalJoker The Practical Joker]]", passing through an energy field causes the ''Enterprise'' computer to play jokes on the crew. Captain Kirk pretends to be scared of the field and tricks the deranged computer into [[NowDoItAgainBackwards taking the ship through the field again]], which reverses the effect that made the computer go bonkers.
* BroadStrokes: The timeframe this series depicts is an accepted part of ''Franchise/StarTrek'' lore, but the actual details have been rearranged since.
* BuildLikeAnEgyptian: Kukulcan's city in "How Sharper than a Serpent's Tooth" has the Mayan pyramids.
* CanonDiscontinuity: The series was declared non-canon by Creator/GeneRoddenberry himself, with the sole exception of the episode "Yesteryear". (Until CBS later declared the whole thing Canon, anyway.)
%%* CanonImmigrant: Creator/LarryNiven's Kzinti and Slavers in "The Slaver Weapon".
* CatFolk: The Caitian Lieutenant M'Ress, as well as the Kzinti in "The Slaver Weapon". Some of the ExpandedUniverse material around it suggests that the Caitian relationship to the Kzinti is essentially the same as the one between the Vulcans and the Romulans, only with the ones that left (the Caitians) being the "good guys" that ended up part of the Federation and the ones that stayed (the Kzinti) as the militaristic bad guys with historic conflicts with the Federation (and possibly with some ill-advised genetic engineering on the part of the Kzinti).
* CatSmile:
** The cat-like Lieutenant M'Ress has one constantly.
** Averted by the Kzinti in "The Slaver Weapon", and in particular their telepath (Kzinti telepaths in general are stated to be manic-depressive).
* ChekhovsGun: In "How Sharper than a Serpent's Tooth", Dr. [=McCoy=]'s medical kit provides a hypo to calm the Capellan Power Cat.
* ChildrenAreCruel: In "[[Recap/StarTrekTheAnimatedSeriesS1E2Yesteryear Yesteryear]]", we get our first glimpse at Spock's childhood... and it's not pretty.
* CloningBlues: In "[[Recap/StarTrekTheAnimatedSeriesS1E7TheInfiniteVulcan The Infinite Vulcan]]", the giant clone of Spock experiences an existential crisis when he realizes he is quite out of scale with the ''Enterprise'' and everything he is familiar with. [[IChooseToStay He ultimately elects to remain on the planet.]]
* ContrivedCoincidence: "How Sharper than a Serpent's Tooth". If Ensign Walking Bear hadn't been on the bridge, Kukulkan would have destroyed both the ''Enterprise'' and the entire human race.
%%* CoolOldGuy: Captain Robert T. April in "The Counter-Clock Incident".
* CreatorInJoke: Captain Robert T. April in "The Counter-Clock Incident". April was the original name for the character that eventually became Kirk.
* DarkerAndEdgier: Than most other cartoons on television at the time. ''The Animated Series'' tended to work with the same style of cerebral stories that the previous live-action series did, and [[NeverSayDie references to death were not glossed over at all]]. In fact, "Yesteryear" deals with [[spoiler:a child version of Spock losing his beloved pet]], and the "death words" weren't glossed over or replaced with LighterAndSofter equivalents. This has helped the series gain a strong following within the ''Franchise/StarTrek'' fan community, as well as with the creative staffs involved with the franchise.
%%* DerelictGraveyard: "The Time Trap".
* DetachableLowerHalf: The title character in "Bem" has the ability to separate his body into different parts.
%%* DetachmentCombat: The title character in "Bem".
* DidWeJustHaveTeaWithCthulhu: In "Once Upon a Planet", several characters end up roasting marshmallows with the dragon that was trying to kill them a few minutes earlier.
* DidYouJustPunchOutCthulhu: "The Magicks of Megas-Tu" has ''[[CoolVsAwesome James T. Kirk defeating Satan!]]'' (Or at least a being claiming to be him as part of a SecretTestOfCharacter.)
* DoesNotLikeShoes: Bios of M'Ress, a BarefootCartoonAnimal, take pains to point this out.
* DolledUpInstallment: "The Slaver Weapon", from Creator/LarryNiven's "[[Literature/KnownSpace The Soft Weapon]]".
%%* DoomedDefeatist: Subverted with M-3-Green in "The Jihad".
* EmpoweredBadassNormal: Kirk (and a few others) gain magical abilities in "The Magicks of Megas-Tu".
%%* EnergyBeings: "Beyond The Farthest Star", "Bem".
%%* EnthrallingSiren: "The Lorelei Signal".
* EveryoneIsASuper: "The Magicks of Megas-Tu" has beings who have the ability to practice magic.
%%* ExpressiveEars: The Kzinti in "The Slaver Weapon".
%%* ExpospeakGag: Between Spock and [=McCoy=].
* {{Fainting}}: Kirk does something akin to the exhaustion- or anemia-based variety in "Albatross" when ThePlague kicks in. Luckily, Spock is there to catch him.
* FemalesAreMoreInnocent: "The Lorelei Signal". The women of the planet Taurus II are effectively psychic vampires who drain the energy from men to survive, [[InferredHolocaust and have been doing so to the crew of passing ships for at least 150 years]]. They try to do the same to Kirk, Spock, and Dr. [=McCoy=] and are only stopped by threat of force from Uhura... yet they're still presented as sympathetic to both the viewer and the heroes because they "cannot bear children," and the end of the episode has the ''Enterprise'' crew promise them [[KarmaHoudini a ship to be able to leave their planet and thus escape the "curse" of immortality]].
%%* FilmingForEasyDub
* FishPeople: "The Ambergris Element" features fish-like aliens who can only breath underwater.
* FiveYearPlan: The three seasons of ''The Original Series'' and the two seasons of ''The Animated Series'' comprise the "five-year mission to explore strange new worlds" from the famous OpeningNarration (which is present in full in this series).
* AFormYouAreComfortableWith: "The Magicks of Megas-Tu". The inhabitants of Megas-Tu do this for their own bodies and their planet's surface for the benefit of the ''Enterprise'' crew.
* ForWantOfANail: In "Yesteryear", if Spock hadn't saved his past self, he wouldn't be alive in order to be part of the ''Enterprise'' crew.
* ForgottenPhlebotinum: "Life-support belts" that allow the crew to survive in vacuum without spacesuits only ever appear in this series.
* FountainOfYouth: The reverse-entropy universe in "The Counter-Clock Incident".
* FourFingeredHands: Spock, in a blooper in "Yesteryear".
* FriendlessBackground: "Yesteryear" lets us see Spock having this. His agemates torment him endlessly for being "a Terran" and Sarek, who expects his son to act like a Vulcan, is disappointed by Spock reacting to their teasing.
%%* GiantFlyer: "The Infinite Vulcan" and "The Eye of the Beholder".
* GirlsNightOutEpisode: In "The Lorelei Signal", Uhura and Chapel have to lead an all-female rescue team due to the planet's inhabitants' ability to drain men of their life forces.
* GodGuise: Keniclius 5 with the Phylosians in "The Infinite Vulcan", and Kukulkan by the ancient Mayans in "How Sharper than a Serpent's Tooth".
%%* GrandfatherParadox: Spock in "Yesteryear".
* HauntedTechnology: The ''Enterprise'' computer gains a prankster personality in "The Practical Joker".
* HealingHands: "The Infinite Vulcan". Spock's clone revives his original with a mind meld. Because of the difference in scale (the clone is a giant), he uses just one fingertip.
* HighTechHexagons: "Beyond the Farthest Star". The Enterprise crew discovers a highly advanced alien ship in orbit around a dead star. The alien ship's interior structure is made up of interlocking hexagons.
* HolodeckMalfunction: "The Practical Joker" includes a proto-holodeck in the ''Enterprise's'' rec room long before ''TNG's''. [=McCoy=], Uhura, and Sulu are trapped in it when the ''Enterprise'' computer gains a trickster mentality.
* HollywoodPsych: "Mudd's Passion" mixes up two types of love: friendship and eros.
* HumanAliens: Although there are still a fair few, this show takes advantage of the animated format to avert the trope whenever they can and come up with more divergent alien designs.
* HumanityOnTrial: "The Magicks of Megas-Tu." Humanity is put on trial by the Megans, for the crime of being xenophobic jerks. The trial is actually for "humanity and those who would aid them" in order to account for the nonhuman crew members. Humanity initially has its sentence suspended because it is concluded that they do not pose a threat to the Megans since it is nearly impossible to locate the Megan homeworld. Humanity is found not guilty after Kirk risks his life to protect a Megan who had been sentenced to a FateWorseThanDeath for associating with humanity. When asked why they didn't just use the ''Enterprise's'' records to discover for themselves that humans were capable of things like a HeroicSacrifice, the Megans reply the records could have been faked.
* ImprobablyHighIQ: The Lactrans in "The Eye of the Beholder". A six-year-old Lactran has an IQ in the thousands.
* InSpaceEveryoneCanSeeYourFace: Life-support belts take this to its logical extreme--the production team doesn't have to draw spacesuits, but can simply use its normal character models with a belt and a glowing outline.
%%* IncredibleShrinkingMan: "The Terratin Incident"
* IndyHatRoll: In "Once Upon a Planet", Kirk leaps through a sliding rock door in the side of a mountain just before it closes.
* InstantAIJustAddWater: The planetary computer in "Once Upon a Planet" develops artificial intelligence on its own.
* IntelligentGerbil: The Kzinti in "The Slaver Weapon", and the Caitian M'Ress.
* ItBelongsInAMuseum: Sulu in "The Slaver Weapon". Spock sets him straight.
* ItIsPronouncedTroPAY: In "The Pirates of Orion", Orion is pronounced "OH-ree-on".
%%* JustBetweenYouAndMe: Charr in "The Jihad".
* LifeDrinker: "The Lorelei Signal". The women of the planet Taurus II drain the LifeEnergy of men to maintain their youth, causing RapidAging in the men.
* LimitedAnimation: Creator/{{Filmation}}'s SignatureStyle. Lacking much range in facial expression, the onus was on the voice cast to convey the characters' emotions, which (being made up of mostly ''Original Series'' alumni) they largely succeeded.
* LosingYourHead: The title character in "Bem" has the ability to separate his body parts.
* LostColony: Terra Ten in "The Terratin Incident"... only it wasn't really lostójust shrunken to an extremely tiny size.
* LotusEaterMachine: In "How Sharper Than A Serpent's Tooth", the animals in Kukulcan's zoo believe that they are living in their natural environment, a hallucination generated by Kukulcan's machines.
* LouisCypher: Lucien claims to have been Satan, in "The Magicks of Megas-Tu".
* LovePotion: "Mudd's Passion". Mudd himself thought it was {{Snake Oil|Salesman}}, and is shocked to find out it works.
%%* MacGuffin: The "Soul of Alar" artifact in "The Jihad"
* MeaningfulName: Bem, which means "Bug-Eyed Monster" in SF fandom.
* MegaNeko: The Kzinti in "The Slaver Weapon", as well as Lieutenant M'Ress.
* MerlinSickness: Inhabitants of the alternate universe in "The Counter-Clock Incident" age backwards.
* MobileFishbowl: "The Ambergris Element". At the end of the episode, two Aquans (aliens who can only breathe water) are shown on the bridge of the ''Enterprise'' wearing water-filled helmets on their heads.
%%* TheMole: Charr in "The Jihad".
* MorphWeapon: The titular device in "The Slaver Weapon" has settings from "stun" to "atomic bomb".
* MrExposition: Ensign Walking Bear, a character never seen before or since, just happens to be on duty on the bridge at the proper moment to explain how Kukulcan is important in the history of his people, in "How Sharper than a Serpent's Tooth".
* MyFutureSelfAndMe: Spock uses the Guardian of Forever to travel back in time and meet himself as a child in "Yesteryear."
* MysteriousMiddleInitial: It was actually in this show that Kirk's middle name was first revealed to be Tiberius, though it wouldn't officially enter canon until [[Film/StarTrekVITheUndiscoveredCountry the sixth film]].
* NeglectfulPrecursors: The Slavers' stasis boxes.
* NeverSayDie: [[AvertedTrope Actively averted]], which became a rather large source of controversy in the episode "Yesteryear".
%%* NoMacGuffinNoWinner: The end of "The Slaver Weapon".
* NoOneGetsLeftBehind: Kirk and Spock in "The Jihad" when the Vulcan gets thrown from a vehicle into the path of a lava flow.
* {{Novelization}}: All of the animated episodes were novelized by Creator/AlanDeanFoster for a series of books published as the ''Star Trek Log'' series, 10 in total. Initially, Foster adapted three storylines per book in novella format. The last few books, however, saw the writer take some of the 25-minute teleplays and expand them considerably into full-length standalone novels.
* NowDoItAgainBackwards: How the computer is repaired in "The Practical Joker"--Kirk tricks it into taking the ''Enterprise'' back through the NegativeSpaceWedgie the other way, by pretending to be scared of it.
%%* OceanPunk: "The Ambergris Element"
%%* OffModel
* OpeningNarration: An animated version of the one in ''Series/StarTrekTheOriginalSeries''.
%%* PatchworkMap: "The Eye of the Beholder"
%%* PatchworkWorld: "The Eye of the Beholder"
* PeopleZoo: The Lactrans in "The Eye of the Beholder" capture the away team and put them in their zoo.
* PettingZooPeople: Lieutenant M'Ress is a Caitian, an anthropomorphic cat.
%%* ThePlague: "Albatross", "The Infinite Vulcan".
* PlanetEater: "One of Our Planets Is Missing" features a space cloud that eats planets.
%%* PlantAliens: The Phylosians in "The Infinite Vulcan".
%%* PleasurePlanet: "Once Upon A Planet"
* PortalToThePast: The Guardian of Forever returns from the ''Original Series'' episode "[[Recap/StarTrekS1E28TheCityOnTheEdgeOfForever The City on the Edge of Forever]]" to provide a portal to Vulcan's past in "[[Recap/StarTrekTheAnimatedSeriesS1E2Yesteryear Yesteryear]]".
* PowerPerversionPotential: In "The Magicks of Megas-Tu," Sulu uses the magic of Megas-Tu's plane of existence to summon a beautiful woman... who transforms into Lucien when he goes to make out with her.
* PsychicStatic: Used to defeat the Kzinti telepath in "The Slaver Weapon".
* PreemptiveDeclaration: In "Albatross", when a native from the planet that put [=McCoy=] on trial follows them.
-->'''Kirk:''' Besides, he'll be sure to take advantage when he sees that we've carelessly left our shuttle bay door open.\\
'''Uhura:''' But we didn't, sir.\\
'''Kirk:''' Oh yes. See to that little oversight, will you, Mr. Sulu?
* TheQuest: The hunt for the "Soul of Alar" artifact in "The Jihad".
* RapidAging: What the LifeEnergy draining by the women of Taurus II does to men in "The Lorelei Signal".
* RealMenWearPink: The Klingons in "The Practical Joker" and the Kzinti in "The Slaver Weapon", courtesy of a colorblind director.
* RealityIsOutToLunch: The planet Megas-Tu in "The Magicks of Megas-Tu" is in a part of the universe where reality breaks down. One character has their arm break off of their body and drift away.
* RealityWarper: The inhabitants of the title planet in "The Magicks of Megas-Tu" can bring anything into existence with but a thought. While they were on Earth they were considered to be witches and magicians due to their powers.
* RecycledSoundtrack: Well, duh, it's Filmation. While yes, this was also done on ''The Original Series'', it definitely wasn't to the same extent.
* ReplacementGoldfish: Carter Winston (actually a shape shifting alien).
%%* RetGone: Spock in "Yesteryear".
* RippleEffectProofMemory: Only Spock and Kirk remember the original timeline in "Yesteryear".
%%* RiteOfPassage: The Vulcan kahs-wan in "Yesteryear".
* RoboSpeak: Any computer voice done by James Doohan.
* RoleReprisal:
** The entire cast, minus Creator/WalterKoenig, reprise the roles they played on the original seriesóCreator/WilliamShatner as Kirk, Creator/LeonardNimoy as Spock, Creator/DeForestKelley as [=McCoy=], Creator/JamesDoohan as Scotty, Creator/GeorgeTakei as Sulu, Creator/NichelleNichols as Uhura, and Creator/MajelBarrett-Roddenberry as Nurse Chapel.
** Instead of providing Chekov [[TheOtherDarrin another voice actor]], they instead replace him with two new characters: Arex (voiced by James Doohan) and M'Ress (voiced by Majel Barrett). Koenig would wind up contributing to the series by writing the episode "The Infinite Vulcan".
** For guest stars, Mark Lenard reprises his role of Sarek in "Yesteryear", Stanley Adams reprises his role of Cyrano Jones in "More Tribbles, More Troubles", and Roger C. Carmel returns as Harry Mudd in "Mudd's Passion".
* {{Rotoscoping}}: How the animation of the ''Enterprise'' was created.
%%* SequelEpisode: "Mudd's Passion" is a sequel to "I, Mudd", "More Tribbles, More Troubles" is a sequel to "The Trouble with Tribbles", and "Yesteryear" is a sequel to "The City on the Edge of Forever".
* SdrawkcabName: The retlaw plant in "The Infinite Vulcan" (named after Creator/WalterKoenig, the episode's author), and the [[PlanetTerra planet Arret]] in "The Counter-Clock Incident".
* SealedEvilInACan:
** "Beyond The Farthest Star". An evil EnergyBeing is trapped in a 300 million year old starship orbiting a black hole.
** Played with by the eponymous weapon in "The Slaver Weapon". Spock and Sulu discuss the potential for such a weapon to destabilize the entire galaxy if it were to fall in to the wrong hands; however, [[AIIsACrapshoot the weapon is self-aware]] to the extent that it can determine that it's not being handled by an authorized user and [[TakingYouWithMe self-destructs when the Kzinti try to activate it]].
* SecretTest: "The Magicks of Megas-Tu". The Megans test the ''Enterprise'' crew to verify their good intentions.
* SelfDestructingSecurity: "The Slaver Weapon". The title device tricks the Kzinti into using a self-destruct setting to destroy it--and them.
* SelfGuardingPhlebotinum: In the episode "The Jihad", the Soul of the Skorr is protected by a force field.
* SickeninglySweethearts: Spock behaves this way toward Nurse Chapel for a large part of "Mudd's Passion", because he's reacting to a LovePotion.
* SingleBiomePlanet: A Volcano Planet in "The Jihad", an Ice Planet in "The Slaver Weapon" and a Water Planet in "The Ambergris Element".
* SnakeOilSalesman:
** Harry Mudd in "Mudd's Passion", though he is unaware that the LovePotion he's peddling actually works.
** Cyrano Jones in "More Tribbles, More Troubles" tries to convince the ''Enterprise'' crew that his new breed of tribble is harmless, without the ExplosiveBreeder properties of the original. (Instead, they grow so large, they eventually explode into a pile of tribbles anyway).
%%* SpacePirates: "The Pirates of Orion"
%%* SpaceshipGirl: The Enterprise computer in "The Practical Joker".
%%* SpaceshipSlingshotStunt
%%* SpiritualSuccessor: "One Of Our Planets Is Missing" to ''TOS'' episode "The Immunity Syndrome".
%%* StableTimeLoop: "Yesteryear"
* StarfishAliens: Edosians, Vendorians, Phylosians, Lactrans, and M/3/Green. The production team was clearly thrilled to not have to worry about budget constraints when designing the aliens, to the point that they probably went overboard with it. (Also, if the aliens naturally fly, swim, or slither, you don't have to animate them ''walking.'')
* StealTheSurroundings: In "The Terratin Incident", an entire miniaturized city is beamed aboard the Enterprise in order quickly to save the inhabitants from impending doom.
%%* SufficientlyAdvanced: "Bem", "The Eye of the Beholder", and "The Jihad".
%%* SuspiciouslySimilarSubstitute: Arex, to Chekov.
%%* SwissArmyWeapon: "The Slaver Weapon"
* TieInNovel: Creator/AlanDeanFoster wrote adaptations of the episodes, and many ''Trek'' novels reference it.
%%* TemporalParadox: "Yesteryear"
* TheTimeTravellersDilemma: It's unknown what happens to Thelen the Andorian (who replaced Spock as Science Officer) after the timeline is fixed in "Yesteryear".
* ThereIsNoKillLikeOverkill: "The Slaver Weapon", a ''hand weapon'' capable of generating a Hiroshima-like detonation complete with shockwave!
* [[TitleTheAdaptation Title: The Adaptation]]: As noted, however, this is only the case for the re-releases. It originally aired just as "Star Trek," with no subtitle.
* TrapIsTheOnlyOption: Hints of this in "The Pirates of Orion". [=McCoy=] and Scotty are suspicious when the Orion captain asks Kirk to beam down to an asteroid to get the medicine he and his crew stole. Kirk agrees that it's dangerous, but he also knows that "without it, Spock doesn't have a chance."
* TwentyMinutesIntoTheFuture: Thanks to a blooper involving the mustached Lt Kyle, one shot of Scotty working the transporter momentarily showed him with a mustache, five years before his live action mustache's debut in ''Film/StarTrekTheMotionPicture''.
%%* TwoOfYourEarthMinutes: "The Lorelei Signal".
* VengefulVendingMachine: "The Practical Joker". After the ''Enterprise'' passes through a mysterious energy field, the ship's computer starts playing practical jokes on the crew. When Scotty tries to obtain a sandwich from the food synthesizer, it sprays food all over him, including a custard PieInTheFace.
%%* VoluntaryShapeshifting: The Vendorian in "The Survivor".
* WellDoneSonGuy: In "Yesteryear" Spock wants to prove to his father Sarek that he is a true Vulcan by undergoing the Kahs-wan RiteOfPassage.
%%* WhoWantsToLiveForever: The alien women in "The Lorelei Signal".
* WingedHumanoid: The Skorr show up in several episodes.
* WitchSpecies: "The Magicks of Megas-Tu" features aliens who are able to practice magic.
* WorldOfChaos: The planet in "The Magicks of Megas-Tu", and the so-called "Mad Planet" in "Jihad".
* WronglyAccused: In "Albatross", [=McCoy=] is falsely accused of indirectly killing people of a plague they weren't cured of.
* YearOutsideHourInside: This occurs in the titular area in "The Time Trap".
* YouAreInCommandNow: Lt. Uhura in "The Lorelei Signal", something which never happened on the live-action show.
* YouCanSeeThatRight: Kirk to Spock in "The Time Trap" when the Klingon battlecruiser disappears.
* YouWontFeelAThing: In the episode "The Pirates of Orion"...
-->'''[=McCoy=]:''' ''[about to give an injection]'' This won't hurt a bit, Spock.\\
'''Spock:''' An unnecessary assurance, doctor, in addition to being untrue.\\
'''[=McCoy=]:''' That's the last time I waste my bedside manner on a Vulcan.
!! This series provides {{aver|tedTrope}}sions of:
* LighterAndFluffier: One of the main reasons given by Creator/GeneRoddenberry as to why he chose Creator/{{Filmation}} out of all the animation companies who made a pitch at doing ''The Animated Series'' is because they were the only company who didn't suggest giving the ''Enterprise'' crew "funny animal sidekicks". Interestingly, ''after'' getting the job, the idea apparently did surface at pre-production meetings... but it was quickly (and rightly) kyboshed by Roddenberry. Regardless, Filmation didn't let the concept of "funny sidekicks in space" go to waste, and created the live-action series ''Series/SpaceAcademy'' a few years later.