[[quoteright:350:[[ComicBook/TheHitchhikersGuideToTheGalaxy http://static.tvtropes.org/pmwiki/pub/images/h2g2mouse_9567.png]]]]
There's an animal on this planet that's always looked harmless - rabbits or mice or squirrels or hamsters, it doesn't matter. One day, you'll be walking your corgi dog [[FluffyTheTerrible Mr. Flufferkins]] along and suddenly he'll look up at you and say, "Thank you, human, for this relaxing walk and all those times you've scratched my chin, but I'm afraid the [[ScaryDogmaticAliens Nogov 10th Brigade]] is coming here in [[TwoOfYourEarthMinutes five of your Earth minutes]] to [[EarthShatteringKaboom get rid]] of this [[InsignificantLittleBluePlanet small blue planet]] and replace it with a transgalactic outlet mall. However, this is good news: [[BadNewsIrrelevantNews you can spend your last five minutes secure in the knowledge that everyone will be getting cheaper outlets soon]]. Well, except the human race, of course, but these things have to be built. Goodbye." And then he disappears before your very eyes, along with every other corgi on the face of the Earth.

You've just encountered the Alien Animal. These [[AliensAndMonsters aliens]] don't have [[LittleGreenMen green skin]] or [[RubberForeheadAliens rubber foreheads]], they just look exactly like a specific type of animal. Maybe they make up the entire population of that animal on Earth or only part of them. Sometimes they're leaving Earth because they have knowledge about the impending [[TheEndOfTheWorldAsWeKnowIt end of the world]] and sometimes they just like [[AliensStealCable watching television]]. Just [[MST3KMantra relax]] and go with it.

If the alien doesn't naturally resemble an animal but has disguised itself as one through VoluntaryShapeshifting, then TheDogIsAnAlien. If the alien looks like an animal but isn't on Earth posing as one, it's probably an IntelligentGerbil.



[[folder:Anime and Manga]]
* [[MentorMascot Luna, Artemis and Diana]] from ''Franchise/SailorMoon'', who are revealed to come from the Planet [[{{Pun}} Mau]], Sailor Mars' pet Crows Phobos and Deimos may count as well.

[[folder:Comic Books]]
* In one ComicBook/FantasticFour story Reed Richards hypnotized some alien shapeshifters called the Skrulls into thinking they were ordinary Earth cows. Years later those alien cows got mixed in with some Earth cow and some were slaughtered for beef. The alien flesh though gave some people a virus that [[CursedWithAwesome shapeshift their bodies into deadly weapons and detect hidden skrulls]] and it would also eventually kill them. The best part? [[ParanoiaFuel There is no way of telling which cow is a Skrull until you eat it.]]

* ''Film/TheCatFromOuterSpace.'' The lead cat arrives in a spaceship and falls for one of the native cats. Oh, and this is a ''live-action film'' otherwise starring ''humans.''
** In a nice nod to something not unlike realism, he [[TranslatorCollar depended on a jeweled collar for telepathically communicating with humans]] and telekinetic manipulation of objects.
* Frank in ''Film/MenInBlack'' is by all outward appearances a regular pug. However, he is a fully sapient and sarcastic alien.
** In [[RecycledTheSeries the animated series]], he is revealed to be... [[spoiler: an alien that looks almost just like a pug.]]
* Similarly averted in ''Film/{{Zathura}}'', where It's Not A Goat ... and it's not on Earth, either.

[[folder:Folk Lore]]
* There is an old British tale (there are different Scottish and English versions, probably some Irish too) about a man that comes across a funeral performed by cats on his way to home. The deceased is a cat in a crown holding a scepter (or the coffin is closed and the crown and scepter are painted over the coffin). When arriving home he tells the strange story to his wife, moment in which the house cat suddenly exclaims "The Old Tom/Tim/Pete/whatever is dead? Then I'm the King of the Cats!" and promptly runs out of the house.
* The chupacabra that feeds on goats' blood is sometimes depicted as a hairless dog-like animal left behind on Earth by its extraterrestrial owners.

* Also in ''Literature/{{Animorphs}}'', domesticated dogs are the product of Pemalites bonding their souls with wolves before they became extinct. So that counts. Sort of.
** Not an animal example, but one of the sidestories indicates that broccoli was brought to Earth by aliens.
** In an interview, KA implied that ants evolved from the Nesk.
* A Creator/SpiderRobinson story in the [[Literature/CallahansCrosstimeSaloon Callahan]] series reveals that we find cockroaches distasteful because they are the degenerate descendants of an evil alien race of overlords.
* ''Cat-A-Lyst'' by Creator/AlanDeanFoster is another one where cats are really advanced and (mostly-)benevolent aliens.
* Franchise/CthulhuMythos: The Cats of Earth's Dream Lands are notable for their intelligence, grace, ability to leap across the interstellar void and their ongoing war with the Cats of Saturn.
* A fantasy example from ''Literature/{{Discworld}}''. Nobody on the Disc suspects that [[spoiler: dragons]] come from the moon until they actually get there and find a ton of them romping around. [[spoiler: They're still dumb animals, although slightly healthier in their native environment. Intelligent dragons are, of course, [[YourMindMakesItReal imaginary]].]]
* Dolphins and mice from ''Franchise/TheHitchhikersGuideToTheGalaxy''. However, dolphins are never mentioned to be aliens, but rather just much, much smarter than humans. It's ''white mice'' who are the aliens, granted they're HumanAliens in their own plane of existence.
** In ''The Restaurant at the End of the Universe'', we learn that ''Humans'' are in fact aliens as well, descended from telephone-disinfectors, advertising executives, and other "useless" people from the planet Golgafrincham.
** According to [[Literature/TheHitchhikersGuideToTheGalaxy the novels]], it would seem that dolphins are the only native sapient life on Earth.
*** Neanderthals might count as well, or they might just be biological robotic components of the computer designed to find the Ultimate Question. In any case, they all died out after the telephone-sanitisers arrived.
* "In the Doghouse", by Creator/OrsonScottCard and Jay A. Davis (collected in ''Literature/MapsInAMirror''): Dogs one day start speaking human languages and announcing that they're aliens -- and nobody takes them seriously; even when they start demonstrating their advanced intelligence by solving complicated math problems and the like, everybody shrugs it off as just a cute trick.
* The cats in the book ''Star Ka'at'' and its sequels. Earth cats were colonists from a planet of sentient cats; when Earth got in danger, the advanced alien cats went to retrieve the Earth cats.
** Also the trope is played with when it's revealed partway through the story that some of the Earth cats have degenerated to the point where they can no longer respond to the telepathic summons, and it's implied that these degenerate cats may even now '''be''' the mere animals humans thought them to be.

[[folder:Live Action TV]]
* In ''Series/DoctorWho'', it's the [[spoiler:BEES! Okay, not all of them, but a lot of them were and they were going home, back to the planet Melissa Majoria]].
** In "Survival," the Cheetah People's minions the Kitlings look exactly like Earth cats, except that they can teleport.

[[folder:Newspaper Comics]]
* A ''ComicStrip/{{Garfield}}'' cartoon suggests that cats are invaders attempting to subjugate humanity, and that they are responsible for certain seemingly-mindless actions of dogs and lower-class humans.
* In one ''ComicStrip/{{Mandrake The Magician}}'' story, Narda has a dream (OrWasItADream?) about finding out that cats and dogs are two warring alien species; the ones on Earth were spaceshipwrecked here, and have exploited the dumb native humans (specifically, cats the females, dogs the males) to survive in comfort without their technology.
* In '80s ''Ziggy'' Sunday strips, the titular character's pet parrot turned out to be an advance scout for an alien invasion force. This idea since seems to have been dropped.

[[folder:Video Games]]
* ''VideoGame/BaldursGate'': Boo, the [[OxymoronicBeing miniature giant]] space hamster. At least if you take [[CloudCuckoolander Minsc's]] word for it.
** A ''regular'' space hamster (i.e. a hamster living on a spaceship) resembling Boo makes an appearance in VideoGame/MassEffect2.
** Ordinary giant space hamsters does in fact exist in the setting (they were bred by a bunch of crazy gnomes to help power their spacefaring 'Jammers), as does miniaturisation magic, so a miniature giant space hamster could well exist. Unless Boo is an ''Awakened'' Miniature Giant Space Hamster, however, he should be just as intelligent as any hamster.
* Staryu and Starmie from ''Franchise/{{Pokemon}}'' are implied to be from outer space. They're [[StarfishAliens starfish with mysterious psychic powers.]]
** Even more strongly implied are the Clefairy family, [[RidiculouslyCuteCritter space fairies]]. Strangely, this is supposed to be the reason they react to Moon Stones-- which [[FridgeLogic raises interesting questions]] about everything ''else'' that evolves by Moon Stone (Jigglypuff, Nidoran, Skitty, Munna, etc.).
*** It's commonly theorized that the other Pokémon that evolve by Moon Stone are biologically related.
* In the game ''Sheep'' you have to lead the sheep, who have become stupid in the time they were on Earth, back to their home planet.
* Can be created in ''VideoGame/{{Spore}}''; you can make creatures that look rather like real animals...or you can make StarfishAliens.
* ''VideoGame/StarControl3'' had the aliens as ''[[DropTheCow cows]]''.
* Some of the [=NPCs=] from ''VideoGame/SuperMarioGalaxy'' appear to be either bunnies, penguins, bees, and orcas. ''VideoGame/SuperMarioGalaxy2'' actually introduced [=NPCs=] such as hummingbirds and chimpanzees.

* While not intelligent, foxes in ''Webcomic/{{Jix}}'' are, in fact, extraterrestrial. A race of aliens took a group of pre-evolved foxes from the Ambis home-world and deposited on Earth to study divergent evolution on a planetary scale. The pre-evolved foxes remaining on their original planet evolved into Ambis while the ones on Earth (of course) evolved into foxes, making the Ambis the distant cousins of foxes. (In fact, Ambis bear a striking resemblance to foxes.)

[[folder:Western Animation]]
* The dinosaur-like aliens from ''WesternAnimation/ChipAndDaleRescueRangers''. They look like earthling dinosaurs only smaller and more advanced, but during the Late Jurassic Period when they arrived, they ate the dinosaurs' earthling food and became as large as them, but less intelligent.
* In one ''{{WesternAnimation/Darkwing Duck}}'' episode ("Twin Beaks"), the hero gets help from aliens that looks exactly like Earth cows -- though this is not exactly this trope, since it is probably only these cows that are aliens, not all cows on Earth.
** Possibly a ShoutOut to a ComicBook/FantasticFour story in which Reed hypnotized some shapeshifting aliens into [[ShapeshifterModeLock mode locking]] themselves into cows.
* The species of highly intelligent (and highly cuddly) cats from ''{{WesternAnimation/Futurama}}''. [[CatsAreMean They're here to enslave and kill humanity, natch]].
* There's an episode of ''WesternAnimation/InvaderZim'' with warlike alien raiders who look exactly like babies.
* ''WesternAnimation/KidVsKat'': Kat comes from a planet where everyone not only looks like cats, but their language is cat-like, and they have many of the same behavorial patterns as Earth cats. Oh, and there's a race of alien hamsters, too. [[ParanoiaFuel They're everywhere!]]
* ''WesternAnimation/LiloAndStitchTheSeries'': In the "Yapper" episode, Mertle's pet dog, Gigi, is revealed to be one of Jumba's experiments (Experiment 007), designed to look and act like a Shih-Tzu dog, annoying people with its constant yapping.
* In the animated series of ''WesternAnimation/MenInBlack'' it is revealed that Frank the Pug looks very much like a dog anyway underneath his disguise suit.
* On ''WesternAnimation/SouthPark'' Earth is revealed to actually be a massive, millennia-old alien reality show. Apparently every other planet only has one species--a planet of deer, a planet of Asians, etc.--and we're all just forced together so everyone can watch what happens.
* On ''WesternAnimation/TeenTitans,'' an alien is visiting Earth when its intelligent pet, which looks like a green dog, escapes. Meanwhile [[{{Animorphism}} Beast Boy]], who can turn into a green version of any animal, is impersonating a dog. HilarityEnsues.
* On ''WesternAnimation/ReadyJetGo'', Sunspot is kind of a mix of a rabbit, kangaroo, and raccoon.