Some mythological creatures are more famous than others, but a few are so famous that their entire ''species'' has been named after them in the popular consciousness, in a kind of mythological malapropism -- or, alternatively, a singular creature proposed as a unique aberration is adopted by other stories as if it were a species.

Related but distinct from SingleSpecimenSpecies, since the [[UrExample original creature]] may have [[AdaptationDisplacement less-famous]] [[LostInImitation forgotten relatives]], or the original creature might have been [[SingleSpecimenSpecies solitary]] and then turned into a race by [[AdaptationExpansion later authors]]. Either way, there's not just one anymore.

However, A Kind Of One may be portrayed as a SingleSpecimenSpecies in each ''subsequent'' work, [[FollowTheLeader following the original]]; in which case it may be a case of CallASmeerpARabbit since the characters have never seen it before, but [[PopCulturalOsmosis the readers have]]. For instance, someone encountering a creature for the first time may CallAPegasusAHippogriff.

Contrast the inversion, ADogNamedDog, where a character is named after their species instead of vice versa.

Trope name is a reversal of "one of a kind".

See also TropeNamer, UrExample, PublicDomainCharacter.
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!!Examples:

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[[folder:Film]]
* Yoda from ''Franchise/StarWars'' probably deserves a mention here, since his species name was never revealed, and any other member that shows up is invariably referred to as "a yoda". George Lucas himself is said not to want the species named, and so it's almost universally referred to as 'Yoda's Species'. At one point he was even reluctant to allow any other characters of Yoda's Species to be introduced, and even after relenting on this ''very few'' others have appeared. Apparently he hasn't shared his reasoning for ''why'' Yoda's background should be so mysterious.
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[[folder:Literature]]
* Frankenstein - There are dozens of different kinds of {{Golem}}s and [[BackFromTheDead reanimated humans]], but FrankensteinsMonster has become a catch-all.
* Sometimes in the Moomentroll stories, one isn't sure if the word used to refer to a particular creature is its personal name or the name of its species. This is often academic if that is the only example we meet.
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[[folder:Mythology]]
* Chimera - A unique creature, child of Echidna and Typhoeos (aka Typhon) in one version of the Greek myth. It's now synonymous with MixAndMatchCritters (and has a similar meaning in RealLife genetics), and various fantasy games such as ''TableTopGame/DungeonsAndDragons'' include a species of monster inspired by the original individual.
* (The) Hydra - Again, a singular creature so tough that it took Heracles a labor to beat, yet is often a random encounter in many a RolePlayingGame. (Lexicographically, "Hydra" just means water serpent, and is also the name of a genus of tiny underwater animals. ''The'' Hydra of Greek myth was more formally known as the Laernian Hydra.)
* {{Medusa}} - She was only one of three Gorgons, her sisters being Stheno and Euryale.
** The ''VideoGame/GodOfWar'' series alternately refers to the monsters as Medusas or Gorgons, but Euryale is fought in the second game.
** Stheno was a random encounter in (of all things) ''VideoGame/FinalFantasyMysticQuest'', the super-short kiddie-lite version of ''Franchise/FinalFantasy''.
** ''TabletopGame/MagicTheGathering'' had a creature with the type Medusa in an early expansion, but all Gorgons released since have been typed as such (and that earlier Medusa is now legally one too).
** Stheno is also a Boss (a leader of naga-like snake people) in ''[[VideoGame/CityOfHeroes City of Villains]]''
** ''{{Nethack}}'' also gets it right in that "Medusa" is a boss and there is only one of her. Better yet, her lair includes a statue of Perseus...
** Ditto several ''Franchise/{{Castlevania}}'' games, which almost makes up for having "Medusa heads" as mooks in almost every installment.
** Averted in ''The Kindly Ones'' arc of ''ComicBook/TheSandman'', where Lyta meets the two remaining sisters who are still in mourning for Medusa.
** They also show up (or images of them) in ''[[VisualNovel/FateStayNight Fate/Hollow Ataraxia]]'', though like Medusa before they assumed their monstrous forms.
** Medusas are a monster race in ''TabletopGame/DungeonsAndDragons'', apparently female-only; the 2nd edition ''Monstrous Manual'' included a male-only version with the power to restore petrified things to normal, suggesting they were a single species dovetailing their abilities. Since this was stupid and reduced the terrifying impact of the medusa, they are almost uniformly forgotten or ignored. 4th edition adds male medusas back. They don't have snake hair and have a venomous gaze instead of a petrifying one. Gorgons, meanwhile, are metal-headed bulls that breathe petrifying gas.
** {{Pardus}} has a jellyfish-like species named Medusa[[note]]Incidentally, also the name for the "jellyfish stage" of actual cnidarian life cycles, as opposed to the "anemone stage" called the Polyp[[/note]] for its petrifying abilities... and its stronger relatives, Stheno and Eurylae.
** As of ''Discworld/UnseenAcademicals'' there's "a Medusa" in the Ankh-Morpork City Watch (although previous references in ''Discworld/GuardsGuards'' and ''Discworld/FeetOfClay'' talked about gorgons).
** Warhammer has both Gorgons ("Ghorgons", in the Beastmen army) and Medusae ("Bloodwrack Medusae" in the Dark Elf army). The latter are the common snake-bodied, snake-haired she-monster type (though their gaze causes rapid exsanguination, rather then petrifaction), while the former are savage many-armed forest giants similar to giant mutant minotaurs. In fact both are derived from mythological roots - originally a Gorgon (a name which, in Greek, simply means "terrifying") was just a savage lumbering beast, akin to the Middle-Eastern Humbaba. It was only later that the word became attached to Medusa and her sisters, and became their species name.
* {{Pegasus}} - There was only the one in myth, but has since become synonymous with pterippi, or {{Pegas|us}}i, or "pegasoids". Interestingly, Pegasus was more or less Medusa's son... and Poseidon's. Poseidon fell in love with Medusa and raped her in Athena's temple, impregnating her. Athena was furious but since she couldn't take her anger out on Poseidon (her uncle and a god) she turned Medusa into a Gorgon as a curse. When Perseus cut off Medusa's head, Pegasus was born out of her neck.
** In ''TabletopGame/DungeonsAndDragons'' (older versions at least), each Medusa killed has a chance of spawning a Pegasus in this way.
** In ''Literature/PercyJacksonAndTheOlympians'', the Pegasi are stated to be descendants of the original Pegasus. The original is mentioned several times, and his twin brother Chrysaor (who is not a winged horse, but humanoid) appears as well.
* [[ALoadOfBull Minotaur]] - Another unique creature naming an entire species. The original was the result of [[MakesSenseInContext an affair between Minos' wife in a sex-bot shaped like a cow and a magical bull from out of the ocean]]. Granted, this one does make some sense at least: "Minotaur" means bull of Minos, and in some versions the original Minotaur's proper name was Asterion, which would kind of make "Minotaur" even more of a descriptive, species-like name in the first place.
* Inverted in ''Theatre/OedipusTheKing'': {{Sophocles}}, who was familiar with the many unique monsters in Greek mythology, treats "The Sphinx" as a unique monster. But in Egyptian mythology, sphinxes are a species with many members.
* [[OurMonstersAreDifferent Depending on the story]], ThePhoenix is often portrayed as being mortal, but only one existing at a time, usually reborn from its own ashes. Other times, it's a more simple example of this trope, with several existing even if they are all periodically reborn. The same sometimes applies to the unicorn, but that would be more of an inversion, since unicorns were originally an imagined species of animal.
** Some authors try to get around this by calling them "firebirds" as though they were a separate species, and sometimes cutting out the immortality piece. (Note: the "Firebird" of Russian fairytales is the only one of her kind)
** In the MarvelUniverse, it's sometimes been claimed that there's not only just one Phoenix in the universe, but only one across ''all'' universes. Though given that such a concept makes it hard to do WhatIf stories about ComicBook/TheDarkPhoenixSaga (one of the most iconic of all ComicBook/XMen stories and thus fertile ground for alternate retellings, they seem to have quietly retconned that idea years ago. And even within the main MarvelUniverse the "only one Phoenix" concept is kind of cheapened by the fact that fragments of the Phoenix can be split off and still have vast power, and the Phoenix can take on more than one human host simultaneously.
* Lamia was a queen of Libya who became a child eating demon in Greek mythology. Over time she came to be generalized into a broad category of succubi, vampires, and other monsters called ''lamiae''. It also became a name for witches and harlots.
** "Lamia" or "Lamiae" in the NeoClassical sense are usually described as: a) demonwomen who change into snakes, b) demonsnakes that change into women or c) strange half-woman half-snake demon things.
* Empusa was originally a daughter of Hecate with flaming hair who seduced men before drinking their blood and eating them. She was eventually demoted in mythology to a class of spirits called empuse, who served Hecate by guarding roads against unwanted travelers. Later, they were ''further'' demoted to a kind of hobgoblin that bothers Greek farmers in the form of various animals.
** Empusa's other parent, Mormo, was similarly a single spirit who bit bad children that was generalized in to the Mormolyceion.
* ''AgeOfMythology'' allows players to raise armies of mythological creatures, that even have fairly correct [[AltumVidetur Latin]] scientific names (all HalfHumanHybrid are ''Homo x'' - Minotaur: ''Homo taurus'' - others take their known genus - Nemean Lion: ''Leo biaxomus'', Pegasus: ''Equus pegasus'', Phoenix: ''Aquila inferna'' - and when no real life animal exists, a Latin word becomes the genus: - Chimera: ''Draco chimera'', Medusa: ''Gorgon chrysaorus'').
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[[folder:Tabletop Games]]
* Honorable mention to [[EvilUncle Uncle]] [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=2132 Istvan]] from ''MagicTheGathering'', whose creature type used to be "Uncle Istvan" (later changed to "human").
** But you can still have several Uncle Istvans in your deck, since he isn't legendary.
** [[OlderThanTheyThink It's older than that]]: Several creatures from ''ArabianNights'' had unique creature types: [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=2258 Ali Baba]], [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=202619 Ali from Cairo]], [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=202452 Aladdin]]. If that set were made today, they'd be legendary.
** The ''Arabian Nights'' "should-be-legendary" creatures were introduced before legendary creatures existed. This was later explained by a sort of {{Retcon}} in the ''Magic'' novels stating that the plane of Rabiah was split into 1001 alternate-universe versions of itself, so there are actually supposed to be 1001 copies of each of these guys running around. However Uncle Istvan was introduced after legendary creatures already existed but designed before, and as he's from the original default setting of Dominaria he doesn't get the excuse 1000 extra copies.
* Meta-example: 1st Edition ''Advanced TabletopGame/DungeonsAndDragons'' included six varieties of demons in its ''Monster Manual'', each one designated as "Type 1", "Type 2", etc. These type designations were also accompanied by the parenthetical names of infamous members of their type, such as "Balor" or "Vrock". When later editions abandoned the "Type __" naming system, the game's writers simply re-named each of the six varieties after these examples, so the "Type 1 demon" became the "vrock", etc.
* ''{{Warhammer}}'' has many, many examples. As well as the Gorgons and Medusae (see Mythology, above), there are examples of Hydras, Chimeras, Minotaurs, Harpies, Phoenixes, Pegasi and pretty much all the standard fantasy versions of this trope. Of special note is the Kharybdiss, however - a species of sea monster in Warhammer derived from the whirlpool-causing individual monster Karybdis in Homer's Odyssey. Karybdis's traditional mythological partner Scylla does inspire a Warhammer monster, but it is a unique individual (the Chaos Spawn Scyla Anfingrimm), rather than a species (in fact the Kharybdiss bears some similarities with Homer's description of Scylla).
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[[folder:Video Games]]
* Quite common throughout the ''Franchise/SuperMarioBros'' universe:
** [[VideoGame/YoshisIsland Yoshi]] is a species of dinosaur most often referred to as "Yoshis" in all games with others of his kind, with the exception of ''VideoGame/SuperMarioRPG'', in which they were "Yo'sters."
** Toad(s), though they used to be called Little Toadies.
** Birdo(s).
** Kamek, at least in Japanese, where that is also the generic name of the enemy type that is known in English as Magikoopa.
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[[folder:Web Animation]]
* The Cheat from ''WebAnimation/HomestarRunner'' looks vaguely like a short, fat miniature cheetah; he's been referred to as "a The Cheat" and no other creature resembling him has ever been seen (except in ''Cheat Commandos'', which is purely [[ShowWithinAShow metafictional]], [[note]]exceptionally so for a setting where everything else tends to become real,[[/note]] so all the Cheat Commandos characters may be depictions of him). One cartoon shows him hatching out of an enormous egg along with "a lifetime supply of fishsticks" and one of the video games has Strong Bad referring to his "hot mom", though, so possibly there are others.
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[[folder:Web Original]]
* In [[http://laserpotato.deviantart.com/gallery/41360631 The Worm Jeff Saga]], Jeff The Killer is a ''species''. It makes sense, though, as it's an AssimilationPlot by the original Jeff.
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[[folder:Western Animation]]
* ''Disney/{{Dinosaur}}'': "Look at all the Aladars!"
* A rather odd example in ''WesternAnimation/{{Futurama}}''. Observing his behavior, Leela names a pet [[KillerRabbit oh-so-cute creature]] "Nibbler". What does his species ultimately turn out to be called? "Nibblonians". Possible explanations include that [[PlanetOfHats they all]] ''do'' like [[BigEater eating things]], and that the species name is only heard by psychic translation, so it may just have been their choice for her.
* Numerous characters on ''WesternAnimation/TheVentureBrothers'' refer to all vampires as "Draculas," with the exception of Jefferson Twilight, Blackula Hunter - who explains that he refers to black vampires as Blackulas because he can't think of a better name to distinguish them from other vampires.
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[[folder:Real Life]]
* Caesar. It started as [[http://en.wikipedia.org/wiki/Etymology_of_the_name_of_Julius_Caesar part of one man's family name]], then became a term for emperors, spawning both Czar and Kaiser. Hilariously, Julius Caesar once proclaimed "I am not King, I am Caesar" in response to followers of his trying to proclaim him King of Rome -- that's right, he insisted on being called "Caesar" as a show of ''humility''.
* Renard, in France. Before, the French word for fox was "goupil", but after the ''Roman de Renart'', the whole species got the name. Renard (or ''Reynaud'', i.e. Ronald) was a famous TricksterArchetype who was CunningLikeAFox.
** The French word for jellyfish is ''méduse'' (Medusa).
* The Sun, the Moon and the Galaxy... are the generally-accepted proper names of ''Earth's'' sun, moon and galaxy, after they turned out not to be unique. The Galaxy is usually called the Milky Way, which is [[ShapedLikeItself a loose translation of "galaxy" into English]]. Science fiction often refers to the Sun and the Moon as "Sol" and "Luna", which is just [[ShapedLikeItself the same thing]], but with Latin instead of English.
* Two partial examples are the words "ocean" and "psalm," which, while not categories of one, are categories with specific, defined members. An ocean is one of four and only four specific bodies of water: the Atlantic, the Pacific, the Indian, and the Arctic. A psalm is one of the 150 songs or poems in the Book of Psalms. There presumably are not and can never be any other oceans or psalms.
** However, [[http://en.wikipedia.org/wiki/File:World_ocean_map.gif there is some confusion]] as to how the oceans should be divided.
** This also doesn't count oceans that existed in earlier geological epochs (such as Panthalassa), oceans predicted to arise in future epochs via continental drift, the subsurface oceans on Europa and Enceladus that have yet to be explored or named, Oceanus Procellarum on the Moon which isn't really an ocean, or any oceans which may be discovered on Earthlike extrasolar planets in the future.
** The split of the world oceans into multiple oceans is an example, too, as for the Ancient Greeks, the ''okeanos'' was one body of water encompassing the world.
** Also, there are other Hebrew poems who share most if not of the literary qualities of the psalms, and (in the NT) Greek passages written in stylistic imitation. These are usually called "canticles", but is there really that much difference?
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