Dragon

Dragons are reptilian creatures widely depicted in the folklore of several cultures on Earth. Like many mythological beings, they have sometimes being portrayed as extraterrestrial creatures in science fiction, and have inspired the design of several alien species.

Biology
Dragons are characterized in numerous shapes, sizes and forms; ranging from elongated serpentine beings to portly quadrupeds equipped with a pair of large membranous wings. Other types may have avian features such as a beak or feathers. They're often portrayed as highly dangerous beasts, capable of spitting poison, acid and/or breathing fire. They are sometimes depicted as having six limbs: four legs and two large wings; whereas other depictions show them with only four limbs: two wings and two legs. Other kinds may have two or four legs but no wings (and still be able to fly in some cases), and sometimes no limbs whatsoever. Their intelligence also varies: from benevolent sages to mindless killers and practically anything in between.

In popular culture
Extraterrestrial life forms similar to, and/or identified as dragons include the following.
 * The extraterrestrial dragons from Dragon Storm.
 * Several dragon species inhabiting the planet Mongo in the Flash Gordon franchise.
 * Dragons which inhabit Eternia in He-Man and the Masters of the Universe; and Etheria in She-Ra: Princess of Power.
 * The Dragon lady from the Lost in Space episode "The Questing Beast".
 * Another Lost in Space episode, "A Day at the Zoo", features a large fire-breathing reptilian beast living on an unnamed planet.
 * The Pocket Dragons are a species featured in the Season 3 episode "Space Beauty".
 * Warlock the Dragon-Horse from Blackstar.
 * The Soup Dragon from Clangers.
 * Ghidorahs; a race of three-headed dragon daikaiju beasts from the Godzilla multiverse, members include King Ghidorah, Desghidorah, and Keizer Ghidorah.
 * Zok from The Herculoids closely resembles a dragon.
 * Minidrags from Alan Dean Foster's Humanx Commonwealth universe.
 * Dragon-like aliens in the Star Wars universe:
 * Krayt Dragons from Tatooine.
 * The Bogwing from Dagobah.
 * The Mantigrue and the Condor Dragon from Endor.
 * A sapient race from the Star Wars galaxy known as Duinuogwuin or "Star Dragons".
 * The many and varied types of dragons which inhabit the world of the Dragon Hunters.
 * Dragons from The Troop.
 * Space Dragons and Zebesian Dragons from Metroid.
 * Genetically engineered Jamyn Dragons from The Norby Chronicles.
 * The Fuolornis Fire Dragons from the planet Brequinda in The Hitchhiker's Guide to the Galaxy.
 * One of the multiple species evolved from the primordial alien life form in Evolution closely resembles a dragon.
 * Dragons are depicted as an extraterrestrial species in the Doctor Who comic story "Dragon Attack", featuring the Eleventh Doctor.
 * The First Doctor briefly met a dragon on the planet Gemino in the comic "The Secret of Gemino".
 * The biomechanoid entity from the Doctor Who serial "Dragonfire".
 * A planet inhabited by dragons is briefly mentioned in the Doctor Who novel The Glamour Chase.
 * The Leaf Dragon from the Doctor Who spinoff series Class.
 * The Velantians from Lensman are a vaguely dragon-like race.
 * In Star Trek: The Animated Series, the alien entity known as Kukulkan has been identified as the source behind legends of dragons and winged serpents from several Earth cultures
 * The Maravel Dragon is one of the species kept by the Lactran zookeepers in Star Trek: The Animated Series.
 * One Enterprise episode mentions that a Vulcan ship has discovered a species of large, fire-breathing reptiles on the planet Berengaria VII.
 * Dragons from Dragon Flyz.
 * Dragons from Ben 10.
 * Fillian Dragons from Sakaar are featured in Marvel Comics.
 * The entity from the Space: 1999 episode "Dragon's Domain" is referred to as one; although it doesn't actually bear any physical resemblance to a typical dragon
 * While no literal dragon has been seen, the Land of the Lost is inhabited by lake serpents and reptilian creatures, including a large, fire-breathing dimetrodon-like beast, nicknamed Torchy.
 * The "Flying Alien" is a Xenomorph variation that somewhat resembles a dragon.
 * The Lloigor from the Cthulhu Mythos are an energy-based multi-dimensional species, yet are able to assume a reptilian form and sometimes identified as the source of dragon legends.
 * Dragons also exist in the DC Multiverse. Malchior from Teen Titans is an example.
 * The Ender Dragon from Minecraft.
 * Flying Basilisks from Winx Club.
 * The creatures from Jack Vance's The Dragon Masters.
 * The extraterrestrials in Nicholas Crotser's "Law of the Stars", known as Harknans, are identified as the basis behind legends of dragons by several ancient Earth cultures.
 * In Marvel comics, Fin Fang Foom is member of a race of alien dragons called Makluans, while Lockheed is member of a another race of alien dragons called the Flock.
 * In Transformers: Prime, most Predacons take the form of dragons.
 * The dragon-like Larga from Alien Convergence.
 * The Shokan from Mortal Kombat are described as being "half-dragon".