[[quoteright:338:[[WesternAnimation/{{Futurama}} http://static.tvtropes.org/pmwiki/pub/images/brainslug1_1375.jpg]]]]
[[caption-width-right:338:Parasite? [[SuspiciouslySpecificDenial What parasite]]? [[BlatantLies This is just my stylish new hat]]. Ha ha.]]

->(''Zuul is defeated by Anime/GodMars'')\\
'''Emperor Zuul:''' Mars! I can't die! I won't!\\
'''Emperor Zuul:''' My cells are all over the universe! Somewhere out there, I will be reborn!\\
'''Takeru:''' What?\\
'''Emperor Zuul:''' Bwahahahaha! Emperor Zuul of Gishin is only a shell occupied by one of my cells!
-->-- ''[[VideoGame/SuperRobotWarsZ Super Robot Wars Z2: Hakai-Hen]]''

A form of BodyHorror common in {{alien invasion}} plots. Aliens, rather than invading in their own form, insert themselves into (usually unwilling or unaware) humans, whereupon they completely take over the host's body, suppress their will, and generally make them [[NotHimself not themselves]]. They generally do this because their natural form is some kind of grub or other not-very-formidable state.

They may have limited or total access to the host's memory, but can generally fool casual observers. A possessed host typically gains increased strength, and sometimes additional wacky powers. They may also be able to [[VoicesAreMental affect a Voice of Evil]] or [[GlowingEyesOfDoom glowing eyes]], to let the audience know what's up.

This will [[PaperThinDisguise fool]] [[IDoNotSpeakNonverbal everyone]] until the critical moment, even though a possessed host [[GlamourFailure usually starts exhibiting really strange symptoms]] such as a [[TheStoic lack of emotion]], a [[NotHimself surplus of emotion]], violent rampages, festering sores, a [[Series/StarTrekTheNextGeneration flue gill]], or [[ArsonMurderAndJaywalking a penchant for ketchup]].

Sometimes, the possession process actually ''kills'' the host, turning them into a ParasiteZombie with MarionetteMotion. If the host is left alive then they may or may not remain aware while possessed. No matter what the case is, it generally takes a DeusExMachina to remove the parasite without killing the host.

The method by which the parasite enters the host body varies; it might be injected, it may latch on to the host's skull or spine, or it may enter as some kind of [[EnergyBeings Energy Being]]. [[OrificeInvasion Crawling in through the mouth or ears]] is also very popular. Often a FesteringFungus. This trope may also be used as a metaphor for [[ScareEmStraight venereal disease]]. A controlling alien that ''doesn't'' invade the body is TheHypnotoad.

Also, [[SelfDisposingVillain for some reason,]] possessed bodies often [[EverythingFades melt when killed.]]

Very popular in films during the UsefulNotes/ColdWar era, as it made such a handy [[ScaryDogmaticAliens parallel for communism]]. One of the [[GenreSavvy most self-aware]] film examples is ''Film/TheFaculty''.

SubTrope of BodySnatcher. Can overlap with AndIMustScream.

Compare with LivingDollCollector. Contrast TheyLookLikeUsNow, where the {{Masquerade}} is limited to posing as human without being able to replace/control specific individuals. Compare & constrast MarionetteMaster, someone who uses actual puppets.


[[folder:Anime and Manga]]
* Radam in ''Anime/TekkamanBlade'' are tiny arachnids that inhabit and subvert the will of human hosts, who have also been upgraded with the ability to manifest super-armor and summon giant beams and dual-headed spears - the eponymous Tekkamen. The title character in particular has been upgraded to a Tekkaman but escaped before being infected with a Radam parasite. Too bad the rest of his family and friends ''have'' been infected, a fact which powers the angst of the latter half of the show.
* One of these showed up in ''Manga/TheKurosagiCorpseDeliveryService''.
* Bardiel, the 13th Angel in ''Anime/NeonGenesisEvangelion''. [[spoiler:It takes the form of a thundercloud and possesses Evangelion Unit 03, BodyHorror-fashion.]]
* Baby in ''Anime/DragonBallGT'' [[BuffySpeak is an alien cyborg...thing]] who took control of several beings throughout the galaxy, while inside a being he would either (a. plant mind-control eggs (b. leech off their life force and use it to fuel himself or (c. make it a permanent home for himself. [[spoiler:The only person the latter happened to was Goku's pal, [[TheRival Vegeta.]]]]
* Many of the byouma in ''Manga/HokenshitsuNoShinigami''
* ''Manga/SevenSeeds'' has [[spoiler: Yanagi-san]] being injected with insect eggs and functioning just fine, bringing the rest of the team to the insects' lair to become fodder.
** [[spoiler: The Acari X parasitoids from the Ryugu Shelter arc]] seem to function similarly, except they seem able to live for a good few months before any effect is really noticed.
* ''Manga/{{Parasyte}}'': the aliens typically crawl in through the ears or nose and kill the host while preserving the body. This only happens if they manage to reach their host's head. The protagonist manages to trap an alien in his right hand. Another character was "lucky" enough to avoid being taken over completely, but only because the alien was [[ItMakesSenseInContext forced to take over his throat and lower jaw]].
* One of the latter theories presented in ''VisualNovel/HigurashiWhenTheyCry'', is that [[spoiler: [[HatePlague Hinamizawa Syndrome]] is caused by parasites who live [[TheSymbiote inside humans]]. Hifumi Takano said that the parasites will control a person's thoughts, leading them to become paranoid and developing a persecution complex.]] In Tsumihoroboshi, Rena's theory that she got later on in the arc from [[UnreliableNarrator Miyo Takano's scrapbooks]] fits this Trope to a T.
* In ''Manga/{{Toriko}}'' Bogie Woods has this ablity, although he achieves it by [[BodyHorror replacing his host's skeleton]].
* In ''Manga/AzumangaDaioh'', [[CloudCuckooLander Osaka]] believes Chiyo's GirlishPigtails are these.
* In ''Manga/{{Claymore}}'', [[spoiler:this is what the yoma really are. They are parasites spawned from the flesh of a pair of captive dragon people. These parasites infest humans and drive them insane by horrifically mutating them. The only thing that can ease the pain of their affliction is human flesh. The whole story of yoma killing and replacing people is just a cover story. The parasites are merely jumping hosts. Miria has a bit of in-universe Fridge Horror when she realizes this means that the Claymores have been killing unfortunate human victims all along.]]
* The Demon Frog from ''Anime/KirbyRightBackAtYa'' is a NME monster which possesses a host, granting SuperStrength but also [[BrainwashedAndCrazy making the host violent]]. The extent of the frog's influence appears to be based on the personality of the host - the nice and innocent Kirby merely turns into a wicked-looking, mean-spirited bully and vandal, but the already villainous King Dedede [[HulkingOut turns giant, monstrous]] and AxCrazy.
* DIO's fleshbud in ''Manga/JoJosBizarreAdventure'' is a rather savvy version of this trope. It hides itself either behind the host's hairbang or inside the brain, so it is hard to be located. It only invokes evil thoughts to the host, so the victim is controlled into attacking the protagonists as if he is naturally evil. It also has failsafe fuctions that will destroy the host's brain and will try to invade another person if the bud is being removed. Part 4 reveals that those who still had DIO's implant when he died were turned into hideous monsters by the out-of-control cells.
** F.F. in Part 6 is a much more benign version of this. It's a colony of zooplankton that, in order to be able to do such things as "see" and "talk", take over the body of a dead prisoner.
* In ''Manga/{{Inuyasha}}'' there are [[AlwaysChaoticEvil low youkai]], which look like huge snakes and insects. They are much weaker than youkai, which can look like humans. However, they can unite with a person who offers them their soul. This creates a special kind of [[HalfHumanHybrid half-demon]], which looks like a human being, but in its true form is a huge amalgation of demons. These youkai form a new consciousness, and the consciousness of the human is completely dominated by the youkai. [[BigBad Naraku]] was born in this way, and later the princess Sara Asano.

[[folder:Comic Books]]
* ''ComicBook/{{Shazam}}'': Mister Mind, an evil telepathic space-worm from the planet Venus.
* In the ''ComicBook/SheHulk'' graphic novel (this was before she turned to surreal meta-comedy) the Cockroach Horde gets around by infesting human bodies.
* The Vaylen in the ''Iron Empires'' graphic novels and ''Burning Empires'' RPG are worm-like creatures that take over the brains of sapient beings, including humans. They have a variety of [[BodyHorror methods for introducing the worm]], all of which are as painful and {{Squick}}y as you'd expect.
** Some parasites have the decency to crawl in through a cranial orifice, but for a Vaylen to infest a human, a new one has to be made. That's right, an infected doctor will ''[[StrappedToAnOperatingTable drill a hole in your skull]]'' to slip a worm into your brain. And as if that weren't bad enough, once you've been infected, [[AndIMustScream you can never control your own body again]]. You're an immobile meat-puppet forever.
* ''ComicBook/SpiderMan'':
** Introduced in the "Planet of the Symbiotes" crossover and further expanded upon in the "Planet Venom" ''Guardians of the Galaxy'' arc, the symbiotes--or Klyntar--are split into two groups: the heroic Guardians of the Cosmos, who bond to worthy hosts and protect the innocent; and an evil empire of planet-conquering parasites that completely dominate their host's will and ultimately burn their bodies out before eating them and finding a new host.
** A villain called the Thousand worked out that the radioactive spider that bit Peter Parker was the source of Spidey's powers, and ''ate it''. He became a [[TheWormThatWalks conscious infestation of spiders]] that could take over other people's bodies, eventually devouring them from within.
* ''ComicBook/{{Supergirl}}'': In ''ComicBook/RedDaughterOfKrypton'', villain Worldkiller-1 is a parasitic lifeform which infests other alien's bodies.
* ''ComicBook/{{Invincible}}'' has a variant in the Sequids. One or more Sequids attach to a host, which then comes under the control of the Sequid hive mind; however, the Sequids themselves have nothing other than the basic instinct to attach themselves to other creatures unless they have a host to boost their intelligence and unite the hive mind.
* ''ComicBook/BlueBeetle'': The Scarab is ''supposed'' to act like this, turning its host into an agent of the Reach. Jaime Reyes avoided this fate because the Scarab that bonded to him was damaged when it crashed on Earth.
* [[StarfishAlien Starro the Conqueror]] creates numerous miniature versions of himself, which attach themselves to people and make them Starro's army.
* In the Creator/AlanMoore ''Franchise/{{Superman}}'' comic ''ComicBook/WhateverHappenedToTheManOfTomorrow'', Brainiac, his body destroyed, is forced to use Lex Luthor for this in order to work his will. Eventually Luthor [[spoiler: begs for death to be free of his control]].
* An old comic from the classic horror days had a parasite that masqueraded as the hand puppet of a popular entertainer. When the 'puppet' is voted in as president, due to people deciding to protest against the current choices, the truth is revealed. But, before it can be stopped, its brethren all come flooding out of the swamp they're shown to be hiding in. Now that one of their own has been made president, they graft themselves to everyone conquering the US, if not the world.
* In IDW's line of ''Franchise/TheTransformers'' comics, this is how Titan Masters work. Unlike the G1 Headmasters, which worked either as two partners or (in the Japanese Headmaster cartoons) robots that piloted larger, non sentient bodies, Titan Masters take over the body of a larger Cybertronian who's head they've replaced.
* ''Franchise/GreenLantern'': Though they pretend to be [[ZombieApocalypse people brought back from the dead]], Black Lanterns are actually closer to this. The black rings essentially animate and control corpses to provoke emotions from their victims [[EmotionEater in order to feed]]. The actual person is not brought back, which is proven when {{ComicBook/Deadman}} continued to exist as a ghost after his corpse became a Black Lantern.
* In the ComicBook/UltimateMarvel universe the Watchers never show up themselves, and speak by controlling someone. When their agent Rick Jones was in outer space, they did this to him to talk with him... which could seem as if he was discussing with himself, if the reader was not aware of the context.

[[folder:Fan Works]]
* In ''Fanfic/TheSwarmOfWar'', the new Overmind inroduces Spylings, who are capable of consuming a human brain and then taking over from inside the empty skull - with all of the target's memories, of course.
* In ''Fanfic/InSottoVoce'' a poe, Wizzro to be exact, possesses the king. He ends up [[spoiler:killing him by exploding him in front of his daughter Zelda]].

[[folder:Films -- Animated]]
* Mr. Potato Head from ''WesternAnimation/ToyStory'', oddly enough. ''WesternAnimation/ToyStory3'' shows that Potato Head's "consciousness" is actually in his body parts, rather than his actual body. In the film after his body is locked up by the bad guys, his parts escape and end up getting around by attaching onto a tortilla, and later a cucumber.
** Not so odd when you consider that when Mr. Potato Head was first created, his body parts were all he was: you had to supply the potato yourself.

[[folder:Films -- Live-Action]]
* The Strangers in ''Film/DarkCity'' were squid-like aliens driving around human corpses. "You've seen what we are. We use your dead as vessels."
* The Bugs where able to do this in ''Film/StarshipTroopers2HeroOfTheFederation''. In [[Film/StarshipTroopers the first one]] too, but off panel.
* In ''The Invasion'', an extraterrestrial fungus infects people, turning them into soulless drones. In contrast to every previous version of ''Film/InvasionOfTheBodySnatchers'' where the aliens [[ReplicantSnatching kill the originals and replace them with pod-grown doppelgangers]].
* His true body blown up in the first ten minutes, Jason does this in ''Film/JasonGoesToHellTheFinalFriday''. The host bodies die after Jason leaves them (oddly enough, NOT from the damage they take while he possesses them).
* The creature in ''Film/{{Proteus}}'' absorbs bodies throughout the movie and is able to assume their form from then on. The minds of the victims continue to exist within it and are able to surface when it naps after a meal.
* In ''The Kiss'', a worm-like voodoo parasite jumps from the body of a young girl's aunt into her via a kiss. Years later, the parasite strives to take over the body of its current host's niece. The possession allows the host body to grow up, but eventually causes it to rot rapidly, leaving behind a particularly gruesome shell after it leaves.
* Done in two different forms in ''Film/{{Slither}}''. Grant Grant gets infected by a queen bee alien that retains his memories, and it's implied that the two of them are merging personalities, although the alien is clearly dominant. Although he is physically mutating, he is able to convince his wife that it is just a bee sting at first. The rest of the aliens infect people and retain their memories, but the people are completely under their control. They talk and move jerkily and don't even try being stealthy, so it's only natural they don't fool anyone for long.
** This was also the plot of its Creator/DavidCronenberg directed inspiration, ''Shivers'', a horror film made in Canada in TheSeventies where alien slugs invade human bodies and turn them into sex-obsessed zombies (the sex is for the slugs' reproductive benefit, not the humans).
* ''Film/StarTrekIITheWrathOfKhan'' has a non-sapient alien parasite that invades via the ear; as a side effect of the damage it inflicts ''slowly crushing the brain'', the victim becomes highly susceptible to suggestion. This is not a pure example of the trope, as the eel itself does not control the host, but the victims display many of the same symptoms.
* The antagonist in ''Film/TheHidden'' was an icky alien resembling a mosquito larva, which forced its way down people's throats and did the BodySurf routine. One of the two main characters is also one, but from another alien species that doesn't need to change body nearly that often.
* The parasites in Creator/DavidCronenberg's ''Film/{{Shivers}}'' are a toned-down version of this. While they don't fully take over your free will, they [[AnythingThatMoves greatly increase your sex drive]], causing you to infect more and more people. It's [[FanDisservice not as hot as it sounds.]]
* ''Film/TheStuff'' looks like marshmallow cream, tastes good and compels the infectees to consume more and more of it, to the delight of the {{Corrupt Corporate Executive}}s who discover it and start to market it. As the amount of The Stuff in the victim increases, it compels the victim to (forcibly) recommend The Stuff to others while it's slowly dissolving the victim from inside out. Eventually, the [[BlobMonster mass]] exits the victim, leaving behind little more than skin.
* ''Film/TheFaculty'' is a [[PostModernism post-modern]] take on this.
* In the horror anthology film ''Film/BodyBags'', the second segment's eponymous "hair" are actually tiny aliens who need human brains as a food source to survive. They trick vain people into getting their "hair treatment" to acquire new hosts.
* ''Film/InvisibleInvaders'': The aliens possess corpses and makes them attack the living.
* ''Film/{{Honeymoon}}'': [[spoiler:It's eventually revealed that Bea's strange behavior is the result of her being slowly taken over by a puppeteer parasite. She understands what's going on and realizes that there's no way to stop it, so she tries to hold onto herself as long as possible and hide the reality from her husband]].
* Alien Raiders (originally titled The Supermarket) is about humans hunting Puppeteer Parasites.
* The original ''Film/{{Stargate}}'' film featured a race of aliens that visited Egyptian-era Earth and invaded a number of human hosts to become the Egyptian Gods. This is expanded upon in the subsequent TV show (see below)

* What the high spirits do to unsuspecting people in ''Literature/AstralDawn'''s second entry could be considered an example of this trope. They possess people without permission and use them for their own purposes for a temporary period.
* The [[TropeNamer novel]] by Creator/RobertAHeinlein, right down to the physically weak "true form" of ''Literature/ThePuppetMasters''; "Grayish, faintly translucent, and shot through with darker structure, shapeless - (reminiscent) of a giant clot of frogs' eggs."
** By the time it was made [[Film/ThePuppetMasters into a movie]], it was considered a rehash of ''Invasion of the Body Snatchers''. In a case of ExecutiveMeddling, the story was compressed and simplified, and they were given a trendier "reptilian" form. (Ironically, Heinlein's novel was published four years prior to ''Invasion of the Body Snatchers'', so if anything was a ripoff, it was the latter, now more famous work.)
* The book and TV series ''Literature/{{Animorphs}}'' had the dreaded Yeerks, giant brain-controlling slugs. They don't kill the host, have full access to the host's memories, and usually do a pretty good job of pretending to be the host, but they have to leave the host every three days to feed (the temporarily-free hosts are generally locked up in the meantime, but more than once the heroes take advantage of this - as if the Yeerk does not feed within those three days, it automatically leaves the host and then dies.) They're also a ''bit'' more sympathetic, due to not being evolved on a PlanetOfHats -- As it turns out, ''most'' of them simply don't know any better. They are also stuck in a blind slug-type body unless they take over the body of another (both described by a friendly Yeerk ''and'' experienced by Cassie when she morphs into one).
** Also [[spoiler: subverted in that another species, the Iskoort, discovered to be a symbiotic (consisting of vaguely birdlike Isk and the suspiciously Yeerk-like Yoort) are stated to have been engineered so that neither survives without the other (this is implied to be ''why'' they've become of such interest to the Ellimist and Crayak).]]
* In the sci-fi book ''[[Literature/TheLeagueOfPeoplesVerse Radiant]]'', the lead character Youn Suu is inhabited by a non-communicative, red, moss-like alien called the Balrog, and is given evidence on both angles to whether it is malevolent or benign.
* The German space epic series ''Literature/PerryRhodan'' featured a race of alien beings, the "Element of War", in a story arc during the mid-1980s. The aliens, who looked like silvery crabs, telepathically controlled people while sitting on their shoulders (although they could technically cling anywhere to the person's body). They were infamous for increasing the host's aggressions and xenophobia and brainwashing him with their constant telepathic whispers until he shared their warlike SocialDarwinist ideology. Interestingly, the Element of War was itself an artificially created slave race that served an ascended cosmic entity called the Master of the Elements as part of his army, the Decalog of Elements. It multiplied by fission.
* The Souls in Stephenie Meyer's novel ''Literature/TheHost'' are a mostly kind, benevolent race of silvery centipedes who thoroughly believe that HumansAreTheRealMonsters. They infest through the neck and take over the host's mind and body, rendering the host unaware of its surroundings in most cases. On the bright side they cure cancer and keep on making potato chips. Besides their overpowering niceness, the lack of crime and the downfall of good TV acting, the only thing giving the Souls away is a faint neck wound and [[GlowingEyesOfDoom silver reflective eyes]], only visible when bright light is shone at the host's face.
** The invading Souls are also a pseudo-religion, as their impetus to overrun other planets isn't genetic, but rather seen as 'the right thing to do.'
* The entity Tak in ''Literature/{{Desperation}}'' does this as well - but the process of riding along changes the body and causes it to decay if the host's mind isn't strong enough.
* ''Literature/WildCards'' has Ti Malice, a parasitic Joker named after a Voudun Loa. His whole body is like an atrophied, withered fetus and he latches on to a host, leech-like, to feed on their bodily fluids and emotions. Not only does he control his hosts while he's attached, they become addicted to a chemical he secretes, so that even after he releases them they long for his return.
* The handlingers of ''Literature/PerdidoStreetStation'', who are given host bodies of convicted criminals by the government of New Crobuzon in return for doing their dirty work.
* Creator/StephenKing:
** ''Literature/TheTommyknockers'', later made into a television movie. The effect appears to be from radiation at first, and at first it also appears to be beneficial, at least physically. [[SubvertedTrope However]], since the aliens aren't actually in control--the humans just start to think like, act like, and eventually become alien.
** The short story "Gray Matter". A man contracts a fungus from a tainted can of beer that eventually transforms his entire body into a huge fungoid blob monster, and makes him crave beer (and flesh).
* Hivers in ''[[Literature/{{Discworld}} A Hat Full of Sky]]'', which are strange beings akin to bodiless minds incapable of thought. They target powerful beings whose minds it can take over, slowly filling up every space until there is none of the original left.
* Vord Takers from ''Literature/CodexAlera'' are a particularly nasty form of this- once they've taken over, your original personality is ''gone'' beyond recall, and the process is compared to a living death. Mercifully, though, the Takers (like all non-Queen Vord) are dumb as posts and while they can force their stolen bodies to reproduce learned skills, they cannot access memories or impersonate the original person with any accuracy.
** For better or for worse, it's not ''living'' death, it's just plain death. Some taken are described as being rotten and decrepifying.
** It actually seems to vary. Some Taken are essentially zombies, but when Doroga describes the process, he only refers to death of the mind, rather than of the body. Since Takers can control corpses, presumably the Vord just don't look after their Taken's health, leading them to die naturally of thirst or starvation anyway.
* Richard K. Morgan's ''[[Literature/ALandFitForHeroes The Steel Remains]]'' explains zombies this way -- a parasite attaches itself to a corpse and reanimates it.
* Dean Ing's novel Anasazi, concerning parasite aliens who have been living in the American Southwest for centuries
* In ''Stuck on Earth,'' Ketchvar III, a slug/snail-like alien, shoves himself up Tom Filber's nose and takes control of his brain.
* A more benevolent, and yet sad, example occurs in the ''Gastarbeiter'' (Guest worker) short story by Leonid Kogan. There people get contacted by incorporeal entities who have no senses to speak of in their natural state but can possess people and experience the world through them. Any real sensation, even the most tedious or unpleasant, is a blessing to them, so they offer people to supplant their minds for such occasions. At first the agreements seem mutually beneficial: the symbionts get their fix, and the hosts kind of sleep through the whole process, retaining only vague memories afterwards. There're no obvious catches either: the symbionts never possess people forcefully, they take good care of their hosts' bodies, act naturally and postpone any crucial decisions until the host "returns". The sad part is that people get addicted to skipping ever larger parts of their lives, some even "committing suicide" by forfeiting their bodies to symbionts permanently.
* The nanoswarms in Michael Crichton's ''Literature/{{Prey}}'' eventually turn out to be able to do this
* The Sad-Eyes in ''Literature/AConfusionOfPrinces'' combine this and MindRape. They are unpleasant bore-grub type things that drill into a host's head and take control of them, using their psychic powers (Psitek) to control dozens of other hosts. They're named for their lack of control over their hosts' tear ducts, which makes them appear to be crying. This has led to a lot of people with flu being mistaken for Sad-Eye hosts and shot at spaceports.
* The entity called Swarm in ''Literature/GalaxyOfFear'' is actually a carefully designed ''plant'' who, in its natural state, is a small dormant pod. It infects people, turning them into elements of a HiveMind, and uses them to spread the infection by ''shooting vinelike tentacles out of their mouths and eyes''. They don't have to stay close together to be under its control, it can and does pretend a host isn't infected so it can get close enough to [[TheVirus infect others]], and it can control thousands, maybe millions of people. When it was created it took a hundred years and a lot of Jedi Knights to subdue it. Its {{Greed}} in taking new minds and pursuing escapees is its downfall when it escapes.
* The Children of Old Leech, in Laird Barron's novel ''The Croning'', are a form of intergalactic parasite that have been infiltrating humankind for centuries, using human bodies to disguise their their true forms. While their motives remain somewhat mysterious, they're clearly not here to make friends, and characters unlucky enough to discover their existence usually wish they hadn't. They can also be found in many of Barron's short stories, including "The Men From Porlock" and "The Broadsword."
* In ''Literature/TheApocalypseCodex'' by Creator/CharlesStross, the villains are a fundamentalist Christian sect who use parasites to forcibly convert people.
* The ''Literature/HonorHarrington'' series has a scientific version of this with specially designed nanotech that, when activated, can be used to force people to commit simple actions. These actions have included pulling a weapon on the main character, making someone drive their own air car over a cliff, and or even causing someone to [[AteHisGun eat his gun]]. Worse, as we learn thanks to [[TheEmpath Honor and treecats]], the victims [[AndIMustScream are aware of what's happening]] but powerless to stop it.
* ''Literature/ProfessorMmaasLecture''. It happens to a [[spoiler:a human whose nervous system is being directly stimulated and controlled by an army of termites to turn him into a mindless WeaponOfMassDestruction against the [[AntWar invading army of ants.]]]]
* The Rhumians in the ''Literature/SectorGeneral'' novel ''Code Blue: Emergency'' are another benevolent version of this, who usually exist symbiotically with a non-sentient species from the same planet and only bond to sentient beings temporarily and in emergencies. However, even the radically-accepting culture of ''Sector General'' initially find them creepy and assume that they must be evil.
* ''Literature/JackBlank'' features the Rüstov, a group of MechanicalLifeforms who wage an infinite war, conquering planets one by one and consuming every inhabitant on it before moving onto the next. Without their hosts, they resemble mechanical scorpions the size of small dogs. When inside a host, the Rüstov feeds off its LifeEnergy and [[PossessionBurnout the host decays]] [[UnwillingRoboticisation as circuits rise above the skin, bodily fluids turn to oil and rust forms and flakes off]]. The first thing that appears when a host claims a body is the Rüstov eye: a dark ring around the right eye and a line going down the right cheek.
* ''Literature/TheHeritageOfShannara'' has [[TheHeartless The Shadowen]], smoky wraiths who feed off of magic and steal the bodies of other living beings for their own. They tend to take on the personality and characteristics of the things they have possessed as well, so a Shadowen possessing an animal will act like said animal, while a Shadowen possessing a child will behave like an EnfanteTerrible.
* "Literature/IntoTheLookingGlass" has the Dreen, Sentient members of other species can be taken over by them, made part Dreen and forced to control their lower castes for them. The 'sentient controllers' get to keep the use of their minds, eyes and voices, since the Dreen don't really care about any of that, since the controllers really have no choice about serving them.
* ''Literature/JourneyToChaos'': Enforcers are smoke creatures that slip into a mortal's body and commander it by suppressing the host soul. Being creatures of Law, they cannot feel emotion and so their hosts will not express emotion but they have unrestricted access to the host's memories so it's only a minor thing.
* In ''Literature/TheSecretsOfDrearcliffGrangeSchool'', one of the students is in a coma while a parasitic maggot in her brain drives her body around.
* In ''Literature/DinnerAtDeviantsPalace'', the villain is actually the host of an alien puppeteer parasite which travels from world to world feasting on the life forces of their inhabitants. Its true form is a small but nearly indestructible crystal.
* In "Wise As Serpents" by Creator/StephenDedman, a key plot point is the existence of snake-like alien puppeteer parasites whose host bodies can't be restored, so the only thing to do when you come across them is to kill them before they do any damage. Which is fine as long as you don't panic and start killing people who aren't actually host bodies...
* [[spoiler:Lord Voldemort]] does this to [[spoiler:Quirinus Quirrell]] in ''Literature/HarryPotterAndThePhilosophersStone''. This would just be your garden-variety DemonicPossession if it weren't for the [[EvilIsVisceral visceral]] manner by which the parasite [[BodyHorror attaches itself to the host]]: [[spoiler:Voldemort's face grows out of the back of Professor Quirrell's head!]]
* ''Literature/TheBrainEaters'' by ''Literature/TheHowling'' author Gary Brandner involves genetically engineered worms which get inside of people's heads, partially [[BrainFood consume their brains]], and then control what's left of their minds, turning them into homicidal maniacs.
* In Creator/SergeyLukyanenko's ''Literature/LineOfDelirium'', this turns out to be the true nature of the Darloks (in the original [[VideoGame/MasterOfOrion game]], they're just [[VoluntaryShapeshifting shapeshifters]]). They're small snakes about a foot and a half in length, who burrow into a person between the shoulderblades and merge with that person. The Darlok's mind takes over the host's, destroying the personality, leaving only echoes. It's possible for a Darlok parasite to change hosts, although it requires a controlled environment. When Darlok spies are discovered, they typically commit suicide while shouting "Darlok!" After death, the symbiote decays in a matter of hours, and the host's brain decays with it, making autopsy useless. For centuries, they have managed to keep their true nature a secret. After the Empire finally discovers the truth, human security forces start scanning the upper back of anyone passing through a checkpoint for the presence of alien tissue.
* In ''Literature/{{Necroscope}}'' the vampires are really nothing more than parasites, which look like leeches, and occupies human bodies. When they control a human, [[EvilMakesYouMonstrous they give him powers]] that are typical of [[OurVampiresAreDifferent vampires]], but the humans controlled by the parasites are almost always corrupted to evil.
* In ''Literature/TheGordianEvent'' by Lee Deadkeys, the Gordian parasite infects the host through the airways or open wounds, leading to insanity, self-mutilation and extreme aggression. It progressively gains more control over its host as it grows. On maturing, the parasite mimics the real Gordian worm and drives its host to water to spawn.
* ''Literature/Goosebumps'':
** Despite the book's title,the "Unloved" from ''The Haunted Mask'' are actually synthetic organisms that resemble Halloween masks. They gradually fuse to their wearer and transform them into the creature they resemble . Each is different but we only get to know two; a rampaging goblin from the first book,and a bitter, decrepit, "old man" from the sequel.
** The Body Squeezers from the ''Goosebumps 2000'' series are a more traditional example. These crustacean-like aliens take over their hosts by hugging them. Seems silly? Wait till you see [[PainfulTransformation what]] [[FaceFullOfAlienWingWong that]] [[OrificeInvasion entails.]]
* ''The Invader'' by Alfred Coppel. The eponymous alien comes to Earth and takes over one of the primitive biped mammals there to scout out the planet for an AlienInvasion. Unfortunately it only attracts attention everywhere it goes, and the police eventually shoot the host, killing the alien as well. Turns out the host it chose was a gorilla from a zoo.
* Yggdrasil in ''LightNovel/UndefeatedBahamutChronicle'' can implant its seeds (known as Ratatoskr, for the squirrel that climbs Yggdrasil in Myth/NorseMythology) into living beings. These seeds enhance their hosts' strength and regeneration while allowing Yggdrasil to give them orders. A host will suffer severe consequences to their health if they try to disobey these orders, and attacking another host will cause them to soon die.

[[folder:Live-Action TV]]
* The whole premise of the ''Series/WarOfTheWorlds'' television show in its first season.
* Occasional MO of the Gua in ''Series/FirstWave'' (though they more frequently used artificial hosts).
* ''Series/DarkSkies'' was built on this (and ParanoiaFuel, of course.)
* Perpetual MO of the Goa'uld in ''Series/StargateSG1''.
** They're a bit unusual in that they generally operate overtly. They use human hosts for infiltration on occasion, but mostly just to make up for being tiny helpless [[strike:slugs]] snake-fish thingies.
*** They switch to more typical puppeteer parasite tactics beginning in Season 8, when they [[spoiler: take over the Trust and use their money and influence to covertly gain power on Earth, after it becomes clear that the Tau'ri can't be defeated using [[DeathFromAbove conventional]] [[AlienInvasion Goa'uld]] [[OrbitalBombardment methods]].]]
** Also unusually, there's a faction of them (the Tok'Ra) which takes only willing hosts (they naturally give their host a powerful HealingFactor and extend the host's lifetime by at least a century or two, so there is an incentive) and time-share instead of taking over entirely
** Inverted in [[spoiler: ''Cure'', where the citizens of a planet harvest the Goa'uld for their health-boosting abilities. Unfortunately, [[OhCrap they weren't Goa'uld, but Tok'Ra.]] And not just any Tok'ra, but the original Tok'ra Queen Egeria--which, given the eusociality of the Goa'uld species, makes the Tok'ra a more or less doomed race. Because oddly, it never occurred to anybody (except the fans) to [[SendInTheClones clone Egeria]], despite the technology to make a perfect clone of a Goa'uld/Tok'ra being well established by that point in the series.]]
*** The Goa'uld at that point didn't have the technology to clone anyone in Season 6. The cloning of a symbiote was only established in Season 9 with the [[CloneArmy army of Ba'als]].
* ''Series/StarTrekTheOriginalSeries'' used this trope twice. In "[[Recap/StarTrekS1E29OperationAnnihilate Operation: Annihilate!]]", parasitic creatures that resemble flying pancakes attack planetary colonists--and eventually [[TheSpock Spock]]. In "[[Recap/StarTrekS2E14WolfInTheFold Wolf in the Fold]]", the Enterprise crew encounter "Redjac", a noncorporeal parasite responsible for numerous serial killings throughout the centuries. One of the humans it possessed was UsefulNotes/JackTheRipper.
** In later incarnations of the Franchise/TrekVerse, the Trill might be an intentional subversion, as they only join with consenting hosts, with the goal of merging their respective consciousnesses.
*** In fact there seems to be ''competition'' among the humanoid population of the Trill planet to become hosts; Ezri Tigan (later Ezri Dax) is considered slightly odd for not wanting to be joined.
*** However, the Trill in TNG - [[RetCon unlike]] those seen later in ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' - do take over their hosts entirely instead of there being a merging... despite this, it's still portrayed as a desirable thing.
*** Perhaps they are better called puppeteer symbiosis rather then puppeteer parasites.
*** In the book ''Fallen Heroes'', a group of seemingly invincible, ruthlessly efficient aliens invades the station and begins systematically killing everyone. One of them shoots Jadzia and kills her, but the Dax symbiont is still alive. It manages, before it dies too, to animate Jadzia enough to throw an overloading phaser at the alien, killing it.
* ''Series/StarTrekTheNextGeneration'': "[[Recap/StarTrekTheNextGenerationS1E24Conspiracy Conspiracy]]" also had the Federation nearly conquered by Goa'uld-like creatures who possessed the top Starfleet brass. For that matter, there were a lot of possessing aliens in the Franchise/TrekVerse.
** And, if we want to get down to the molecular level, Borg nanoprobes are a form of this.
* ''Series/StarTrekEnterprise''. The Xindi Reptilians infect Hoshi Sato with brain-bugs to make her decrypt the weapons codes of the Xindi superweapon, though she is able to resist for a time.
* ''Series/{{Lexx}}'' did this at least twice. In one instance, the preferred method of insertion was rectally.
* ''Series/BabylonFive'' has two examples.
** The Drakh Keepers, spawned by the Drakh to control other creatures. A somewhat unusual example in that they did not actually take over the host's consciousness: rather, the host remained conscious and more or less free to act normally, but take a wrong step and the Keeper could either impose painful punishment or simply [[AndIMustScream take over the victim's body]]. Keepers had only had two weaknesses: alcohol - which put them to sleep - and to kill the Drakh who spawned the Keeper.
** The Vindrizi symbiotes from "[[Recap/BabylonFiveS03E07Exogenesis Exogenesis]]" [[SubvertedTrope subvert the trope]]. They're assumed to be evil until it's revealed that they're actually [[spoiler: benevolent "recorders" who use their willing hosts to witness history, hoping to prevent that knowledge from being lost in "the next dark age" they anticipate.]]
* ''Series/DoctorWho'':
** Such creatures featured in [[Recap/DoctorWhoS11E5PlanetOfTheSpiders "Planet of the Spiders"]], [[Recap/DoctorWhoS15E2TheInvisibleEnemy "The Invisible Enemy"]], [[Recap/DoctorWhoS27E3TheUnquietDead "The Unquiet Dead"]], the two-parter [[Recap/DoctorWhoS29E8HumanNature "Human Nature"]]/[[Recap/DoctorWhoS29E9TheFamilyofBlood "The Family of Blood"]], and elsewhere.
** ''Doctor Who'' frequently has the "possession kills" version; even if you're sure you can see some of [[IKnowYouAreInThereSomewhereFight your friend/spouse/etc. in there under the evil alien whatever]], if the Doctor says "s/he's already dead," not believing him ''will'' relegate you to {{Redshirt}} status. (Perhaps this is why TheVirus was used in the EverybodyLives story: TheVirus is ''never'' reversible... except just this once.)
** The Master becomes a goo snake that does this in [[MadeForTVMovie the movie]].
* ''Series/{{Torchwood}}'' used this in "[[Recap/TorchwoodS1E2DayOne Day One]]" and "[[Recap/TorchwoodS1E7GreeksBearingGifts Greeks Bearing Gifts]]."
* ''Series/TheOuterLimits1963'' did two vaguely similar alien parasite episodes.
** In "Corpus Earthling", a race of sentient alien rocks are quietly taking over humans--until they're accidentally discovered by the main character, who has a metal plate in his head that allows him to overhear their [[TelepathicSpacemen telepathic conversations]]. (Yes, the creatures apparently [[AliensSpeakingEnglish think in English.]]) Things get interesting when the aliens respond by possessing the hero's wife and best friend...
** "The Invisibles" combines this premise with SpyFiction. An agent of the "General Intelligence Agency" (a FictionalCounterpart of the {{CIA}}) investigates alien parasites who have infiltrated humanity by joining with willing, power-hungry humans at both extremes of society: some of the Invisibles are homeless misfits, while others are political leaders, industrialists and military brass.
* ''Series/TheOuterLimits1995'':
** "Dead Man's Switch" had a very brief scene of ''literal'' Puppet Masters. The protagonist is down in a secure bunker, where he must push a button every hour to prevent Earth's last-ditch DoomsdayDevice from going off. The protagonist's commanding officer is talking to him via video from Washington DC, assuring him that the alien genocide it was meant to avenge is over and they'll relieve him soon, he just has to keep pushing the button until his bunker can be reached. In the episode's final shot, it's seen that [[spoiler:the General is a corpse amidst the buring ruins of DC, and spindly sea-spider-like aliens have their limbs stuck into him through a gash in his back, working him like a ventriloquist's dummy.]]
** "The Second Soul" features a benevolent, mostly-benign version. The aliens are refugees, energy beings who need a body, and asks humanity to give them their dead. There is strain on both sides, with the aliens dying because they can't get a host in time, and some humans being DrivenToSuicide by the stress of knowing that their loved ones are dead, yet also seemingly alive when inhabited by an alien. The end of the episode reveals that [[spoiler:the children of the aliens possessing human bodies are 100% human, which makes sense, considering they don't alter the bodies' DNA. Additionally, one of the humans thinks that the aliens are up to something, when they purchase a large building and start stockpiling deadly gas. He assumes they might try {{terraforming}} Earth. However, the aliens are only interested in building a museum to preserve their culture, as they know that they will die out within a generation and that all their children will be human]].
** "Caught in the Act" has an alien parasite possess young women and seduce men in order to [[{{Squick}} absorb them for food/energy]]. This has happened at least several times throughout history. The parasite can only be defeated with the PowerOfLove.
** "From Within" has prehistoric worms take over a mining town but are defeated by a mentally-retarded kid who figures out that they like salt and hate sunlight. They also cause the host to lose all inhibitions.
* Apparently the premise behind ABC's short-lived series ''Series/{{Invasion}}''. The show was canceled before it could be made clear, but it appeared to be more a case of "replacement" than "control".
* ''Series/BuffyTheVampireSlayer'':
** The episode "[[Recap/BuffyTheVampireSlayerS2E12BadEggs Bad Eggs]]" featured the Bezoar, a prehistoric parasite whose offspring attached themselves to other creatures and controlled their motor functions.
* The [[Recap/AngelS01E02LonelyHearts second episode]] of ''Series/{{Angel}}'' featured a burrower demon, who possessed human bodies and took over their mind, however it had to go from body to body on a regular basis, because once it's been in a body for too long, the body started to deteriorate...sensibly enough, as the initial immolation action would logically kill the victim, with the possessed body then being little more than a still-warm corpse. The third season also [[Recap/AngelS03E19ThePrice had the "sluks"]], transparent crustacean-like demons who entered their hosts through their mouths, the downside being that these creatures required lots of water to survive, causing their hosts to dry down and die.
* ''Series/{{Primeval}}'' had an episode featuring dodos who were infected by some parasite. It spread to some dude, who's personality changed a lot. He also knew he was infected.
* ''Series/QuatermassII''. Aliens from a nearby asteroid reach Earth via hollow meteorites and start infiltrating the upper echelons of society.
* The ''Series/{{Farscape}}'' episode "A Bug's Life" features an "intellant virus"--a highly infectious virus that takes over the mind and body of the infected.
* ''Series/TheXFiles'':
** The arctic worms in the first season episode "Ice" made people agressive and murderous.
** The Black Oil, dubbed "[[FanNickname the oiliens]]" by fans. Took complete control over one's mind and body and was an important part of the MythArc.
* In the sixth season of ''Series/{{Supernatural}}'', the "Mother of All" uses a parasitic worm--[[OrificeInvasion vomited into the ear]], no less!--to control her victims.
** In season 12, the Bisaan were shown. They were cicada-like creatures who [[OrificeInvasion enter people's body through the mouth]] and take control of the host so that they can breed.
* A ''Series/{{Smallville}}'' episode has several characters infected by parasitic worms that caused their hosts to lose all inhibition and fear. The first victim takes a nosedive off a tower. Since Clark can't be infected (it's kinda hard to burrow under unbreakable skin), his infected friends use Red Kryptonite to simulate the same effect in him.
* An episode of ''Series/{{Sliders}}'' has Maggie infected by a bug-like creature that has her acting increasingly erratic, constantly being cold and seeking warmth and then seeking to reproduce by seducing men. When a government official on another world finds out, she is excited at the possibilities, as the "bug" appears to be able to mimic human organs. Since being an organ donor is mandatory for anyone between 18 and 30 in this world, this creature could end the need for young people to die needlessly just because someone else needs a new heart. A noble goal, but she goes about it in a completely wrong way and ends up becoming host to the creature herself, possibly dooming her entire world.
* ''Franchise/UltraSeries'' examples
** Darii from ''Series/UltraSeven'' is an extraterrestrial parasite that feeds on blood, which it does by taking over people's bodies and turning them into vampire-like beings that sleep in the daytime and wake up at night in a trance to search for blood to drink.
** ''Series/UltramanTaro'' had an alien named Kaan, whose species are parasites of kaiju and send their hosts on mindlessly violent rampages. He takes parasitizes the body of a friendly monster named Orphy, forcing Taro to fight it and find a way to get Kaan out of Orphy's body.
** Magnia from ''Series/UltramanTiga'' is a swarm of parasitic creatures spawned from an organic meteorite. The parasites find food for the meteorite by attacking prey and latching on, turning the victims into zombies that march themselves towards the meteorite, which then consumes their life force.
** Cyclometra from ''Series/UltramanDyna'' is a parasite of kaiju that invades their bodies and turns them into mindless zombies as its young incubate inside them. After a while, the kaiju explodes with enough power to destroy everything in a 4-kilometer radius, killing the parasite but sending the young flying through space where they land on another planet and start the cycle anew.
* The [[TheStinger Stinger]] for the mid-season finale for season 3 of ''Series/AgentsOfSHIELD'' was that the mysterious 'It' was actually [[spoiler:an alien brain worm that possessed dead hosts, the most recent of which is Ward.]]

* Bob Drake's "The Persecuting Engine" deals with a protagonist that falls victim to "The Thing" which uses the aforementioned Engine "which, from afar / can influence your actions as we wish, distort your perceptions into indecipherable alien ones, [and] replace your will with ours" on him.
* A noteworthy example of this is Music/CreatureFeature's song "Look to the Skies" which is about aliens that have come to Earth for some sinister reason. The refrain?
-->''We Better Face The Facts,''\\
''The Plan's Been Hatched,''\\
''Duplicate The Perfect Match,''\\
''Then [[BodySnatcher Body Snatch]]''

[[folder:Other Sites]]
* ''Wiki/SCPFoundation''
** [[http://www.scp-wiki.net/scp-378 SCP-378 ("Brainworm").]] After SCP-378 enters a victim's skull it gains control of the brain and controls the body. The victim acts normally while under control, indicating that SCP-378 can read the victim's memories and personality.
** [[http://www.scp-wiki.net/scp-783 SCP-783 ("Baba Yaga's Cottage").]] In [[http://www.scp-wiki.net/interview-log-783-1 Interview Log 783-1]] an animal mutated by SCP-783 grows tentacles that it inserts into a human being's skull in order to take over his brain.
** [[http://www.scp-wiki.net/scp-1092 SCP-1092 ("A Species of Fish").]] After growing to full size inside the victim's body, in some cases SCP-1092 will travel up the carotid artery to the victim's brain and take over their minds. They will use this control to make the victim head for the nearest large body of water so they can exit the body and enter the water.

[[folder:Tabletop Games]]
* In ''TabletopGame/DungeonsAndDragons'':
** The supplement "Lords of Madness" details a race called the tsochari, aka "the wearers of flesh," a tentacled alien that replaces its victim's brain and masquerades in its corpse. Or, if they want to, they can also just ride in a living host, tell him what to do, and hurt him if he doesn't do it.
** Another D&D creature (from core sources this time) is the hellwasp swarm. It can inhabit dead bodies or possess living but helpless (such as from its own poison) creatures, although in the latter case it kills its victim in a few hours.
** Bog Hags in the ''Oriental Adventures'' supplement steal the skin of their victims and use it and their limited shapeshifting abilities to impersonate mortals.
** Puppeteers from the Expanded Psionics Handbook take over the body of anyone that they are in contact with.
** Mind Flayers are another monster that ''reproduce'' in this fashion. A mind flayer tadpole is inserted into the ear of an unwilling (usually) host, and through the process of ceremorphosis, the host eventually turns into another mind flayer.
*** For extra fun, the Mind Flayers of Thoon (who are freakish and twisted even by Mind Flayer standards due to contact with... ''something'' from [[CosmicHorror The Far Realm]]) have two specialized parasites to take over humanoid slaves for their masters' purposes: Thoon infiltrators (ExactlyWhatItSaysOnTheTin; the transformation effectively kills the original as the parasite remakes the whole inside of the body) and Thoon thralls (cannon fodder {{Action Bomb}}s [[AndIMustScream who aren't so lucky as to be "killed" by their infestation]]).
** When Olive Slime touches a creature, it spreads over the victim's body and its secretions affect the victim's brain. Over a period of 7-12 days the victim will turn into a vegetable creature controlled by the slime.
** Intellect Devourers, which actually look like really big brains on four legs, can [[AWizardDidIt somehow]] cram themselves in a victim's cranium, devouring their brain in the process, and can animate the body as a puppet for a while afterwards. Bonus points for its [[YourHeadAsplode particularly messy]] way of exiting its host body after it's done with it.
* Roach Thralls from the Urban Arcana supplement for the TabletopGame/D20Modern game. The species reproduces by laying eggs inside a living human body, and their larval forms consume said human's brain and internal organs while leaving a sufficiently human-looking carcass to disguise their (somewhat compressed) cockroach form. After 6 months to 2 years, the creature still looks human but can produce and implant eggs of their own into human hosts. The Roach Thrall can shed their human skin if necessary, but this one-way process also renders them unable to reproduce, even with other unmasked Roach Thralls. In the wrong game master's hands, this creature could scare players off of sex for life.
* The Kyriotates from ''TabletopGame/InNomine'' are a benevolent version of this. They're angels who can control bodies (multiple bodies at once no less!) but they usually only borrow the bodies of willing hosts or non-sapient ones, and do so in the name of good, taking care not to leave the host's body in an injured condition or do things with the borrowed bodies that would cause the host problems. Their {{evil counterpart}}s, the Shedim also posses their hosts, but are limited to a single body at a time and are [[TheCorruption driven to make their hosts commit increasingly evil acts]]. The insidious part is that the host's consciousness is still there and thinks it's still in the driver's seat. Once the host reaches the MoralEventHorizon, the Shedite leaves and the host is left teetering on the brink.
* The ''TabletopGame/OldWorldOfDarkness'' sourcebook ''Blood-Dimmed Tides'' introduced malevolent octopus things that wrap invisibly around the victim and drill a tentacle into the base of their neck. Three guesses what happens next.
* In ''TabletopGame/NewWorldOfDarkness'':
** The Hosts from ''TabletopGame/WerewolfTheForsaken'' sometimes get around the mortal world in this manner.
** The [[OminousOwl strix]] from ''TabletopGame/VampireTheRequiem'' are also a variant of this. Normally disembodied spirits that take the form of owls, they can possess humans (usually killing the host) or vampires who are torpored or currently out of their body. They don't gain any access to the host's memories, though, and their motivations typically run from "wreck vampires for the lulz" to "[[SenseFreak experience everything I can, now that I have these strange things called nerve endings]]."
** The "Wicked Dead" sourcebook brings other examples, such as ''cymothoa sanguinaria'', which takes over a human body, overriding the consciousness and [[BodyHorror eventually replacing the tongue]] in its search for blood, and the Ragged Man, a parasitic virus that only activates in vampiric blood, drawing Vitae from them until it matures, at which point the vampire in question pukes it up into a source of water and continues the transmission.
* In TabletopGame/{{Ravenloft}}, sea spawn adults ("masters") use their larvae ("minions") to procure victims from coastal villages. The larvae burrow into human hosts' spines and usurp control of their nervous systems. Each host spends a few days luring or forcing innocent victims into the surf, where the hungry sea spawn master awaits, then feeds ''itself'' to the master once it's too ravaged by the minion's brain-nibbling to last much longer.
* ''TabletopGame/{{GURPS}} Black Ops'' has the Brainsuckers. As the name suggests, they don't just control the host, they also eat his brain to feed their offspring.
* The Vrakylaks in ''TabletopGame/{{Eon}}'' are a species of semi-sentient, crawling organs that embed themselves in the neck of their victims, manipulating them ether through promises of release or threat of violence (they're attached to their nervous system after all) to kidnap more people and bring them to a nest. When the time is right, all the little Vrakylak's newly hatched spawn crawl up to the secured victims, and the cycle begins anew. Oh, and victims progressively go blind from the symbiosis.
* As of their latest codex, TabletopGame/{{Warhammer40000}}'s Necrons have these in the form of Mindshackle Scarabs, which are occasionally used to subvert and conquer worlds.
** There are also enslavers, Chaos beings that can mind control pretty much anyone. They are always more compared to a plague than a species.
* ''{{TabletopGame/Rifts}}'' has at about a half dozen types of these. Some are monsters, at least two are available as Player Characters.
* ''TabletopGame/YuGiOh'': Judging from Verz Heliolope, more than just being a virus born from the bodies of fallen Inverz monsters (Infestation Infection), it can be said that it is an infection that carries the soul and will of the Inverz, thus any monster infected by it, became a slave to their will. For example in Trial and Tribulation, we see Gishki Noellia mourning who seems to be Gishki Natalia before becoming a spirit, all these while the Verz Infection lurks around her, with none other than Inverz Grez in the background, later the infection grows (Creeping Darkness) and she becomes half Evigishki half Verz (Evigishki Psychelone). Another example is Constellar Meteor where we see Constellar Castor charging against Evigishki Psychelone while the same Verz Infection (from Trial and Tribulation) seems to approach him. So, more than just being a self-defense mechanism in case of extermination, the Verz Virus is actually an amalgamate of the Inverz souls searching for new bodies in order to fulfill their objectives.
* ''TabletopGame/{{Nobilis}}'': the player characters, Nobles, can do this. Those who are ghosts, or titles, or articles of clothing, or other weird stuff, may have no other choice if they want to move physical objects.
* Dr Ludwig Ritterbach from ''TabletopGame/RocketAge'', a Nazi scientist on Mercury, is under the control of a modified Venusian slug which is planning to use his body to breed more of its kind.

* The Krana in ''Toys/{{BIONICLE}}'' are a rare external, visible example, combining this trope with FaceHugger. The Kraata were supposed to be this for the toys, but were changed in-story somewhat.
** In another Franchise/{{LEGO}} example, the ''Toys/LEGOAlienConquest'' line features "clinger" accessories which attach to a mini-figure's head. Because modern mini-figures have two facial expressions (the unusued one is hidden by a hairpiece or hat), the face can be turned around to show terror... or bland submission. They're also a visual ShoutOut to the brain slugs from ''WesternAnimation/{{Futurama}}''.
** The 2013 ''Toys/HeroFactory'' line focuses on the heroes fighting what are described as evil brains that latch onto beings and turn them into monsters.
** The 2015 ''Toys/{{Bionicle|2015}}'' reboot has a SpiritualSuccessor to the Krana with the Skull Spiders. The Lord of Skull Spiders was at one point going to be called the Skull Krata as a ShoutOut to the earlier series.

[[folder:Video Games]]
* The Venusians in ''[[VideoGame/MetalSlug Metal Slug 6]]'' has this to possess soldiers in China. There's a purple EliteMook variant in the [[WombLevel Venusian Nest]], who possesses your teammate and turns him or her into [[MirrorBoss Allen O'Neil]] {{expy}}.
* The original Zerg, from ''VideoGame/{{Starcraft}}'' did this, according to the background. In the game, they can still "infest" people, though the victim's appearance changes drastically.
* In ''VideoGame/StarcraftII'' the infester takes this role with the "neural parasite" ability. This one isn't very subtle either, as the unit under its control still has a 20 foot tentacle jutting from the back of their head, creating a direct link to the infester and its host. Furthermore, the control is only temporary. That's not to say it isn't useful, as more advanced players can take control of a worker of their enemy and construct a base that's the same type as the enemy you're fighting, effectively giving you control of both the zerg and whatever race you're fighting. The neural parasite is not limited to biological units either. Battlecruisers, Carriers, Colossi, and all other manner of mechanical units are fair game.
* The Throne of the Tides dungeon in the ''VideoGame/WorldOfWarcraft'' "Cataclysm" expansion features a boss, Erunak Stonespeaker, who is being mind controlled by a creature that attached itself to his head. It will also mind control random players during the encounter.
** The Merciless One species is also encountered earlier in Vashj'ir. Ozumat appears to be a very big version.
* ''VideoGame/ResidentEvil4'' introduces Las Plagas, parasites which turn their infectees into brainwashed slaves for control plagas. Ganados from ''4'' and Majini from ''5'' are infected with Plagas.
** There are some [[ApocalypticLog research notes]] left behind by [[spoiler:Luis]] which talk about some [[TruthInTelevision real life]] parasites that do this to small insects and the like.
** [[AllThereInTheManual According to various files]], the Nemesis from ''VideoGame/ResidentEvil3Nemesis'' is a Tyrant with a pupeteer parasite controlling it.
** A variant of said parasite, known as the "NE-β Type", appears in the [[FanonDiscontinuity non-existent]] ''VideoGame/ResidentEvilOperationRaccoonCity'', which latches onto hosts (zombies and, in one case, a Tyrant) in the game to control them.
* In both ''VideoGame/HalfLife'' games, the iconic headcrabs kill people by jumping at them and then latching onto their heads to turn them into much stronger zombies. In the second game, the villains even use missiles filled with headcrabs as weapons. Which when you think about it might not be always be a smart idea when you consider the headcrabs aren't actually on their side either; places like Ravenholm ended up literally crawling with zombies as a result of excessive headcrab-bombing.
** It's worth mentioning that players discovered a particularly horrifying fact about headcrab zombies: Playing the audio of their voices in reverse reveals that their human hosts are actually [[FateWorseThanDeath still conscious and screaming bloody murder]] from under their fleshy puppetmaster of a hat.
** This can be seen when you forcibly remove a headcrab from a person's head: the host's face is contorted it bitter agony, although it is missing most of its ''skin'' and ''[[EyeScream eyes]]''.
* In ''VideoGame/MassEffect1'' a colony is taken over by the Thorian; a giant plant controls unsuspecting victims with spores and forces them to do as they wish or suffer extreme pain. This gives the Thorian so much power over its subjects that they will fight to the death rather than disobey - [[spoiler:except for the colony's leader, Fai Dan, who resists its order to kill Shepard long enough to commit suicide. Nice work.]]
* The bonethieves from ''VideoGame/EternalDarkness: Sanity's Requiem'' are a particularly nasty example. First they burrow into their victims' chest, then guide them around like puppets. Then, when the host body takes enough damage, the bonethief burst through in a shower of gore, which isn't exactly healthy to your sanity, and tries to burrow into ''your'' chest.
* This is the overlying threat you're trying to defend against in ''VideoGame/XComApocalypse'', as the aliens use aptly-named creatures called Brainsuckers to give people a FaceFullOfAlienWingWong and put them under alien control. If a Brainsucker converts one of your soldiers in this manner, they're dead as far as the game is concerned.
* The Oktigi of ''VideoGame/{{Oddworld}}: Stranger's Wrath'' are a race of Octopi-like creatures that function like the Brainsuckers above. It is revealed that [[spoiler:Sekto is of this species, who after defeat [[VillainExitStageLeft leaves the body of the Olden Steef and escapes into the river.]] ]]
* The Necromorphs in ''Franchise/DeadSpace'' are a subversion of this. The Marker causes those nearby to go crazy and start killing people, and then takes over the dead bodies.
** Also, a rather disturbing death animation a certain necromorph also qualifies. After taking enough damage, the necromorph will fall to pieces, which will still attack Isaac. If the piece that was the monster's head kills Isaac, it will decapitate him, root itself on his neck, and take over his body.
* In ''VideoGame/DestroyAllHumans'', body-snatching becomes Crypto's primary way to disguise himself amongst humans by the second game.
* The Nomads/[[AllThereInTheManual Slomon K'Haara]] in ''VideoGame/{{Freelancer}}'' are this, with aspects of TheVirus: it is strongly implied that Nomad-infested humans can infest other humans as well.
* The Morphoids in ''[[VideoGame/NicktoonsUnite Nicktoons: Globs of Doom]]'' can pull this; while they can fight on their own, the bosses (except for BigBad Globulous Maximus and two of the bosses in the DS game) are all infected characters with a head full of Morphoid goo.
* ''Franchise/{{Pokemon}}'' has a case in the form of Paras and Parasect. Paras is a simple bug being slowly eaten alive by the mushrooms on its back, the bug making the best of its situation by using them for self-defense. Parasect is this same bug, virtually dead and covered with the mushroom, which has overridden the insect's nervous system.
* The Flood in ''Franchise/{{Halo}}''. They use fleshy pods to evolve into small, bulbous creatures full of tentacles. Once they find a suitable host, the Infection Forms attach and paralyze the victim before '''ripping open the chest cavity and nestling inside''', taking over the host's nervous system and beginning rapid mutation, culminating in a real ugly abomination known as a Combat Form. Though the host is technically dead, the controller retains enough of the host's experience that Combat Forms are decent marksmen (!). In some cases however, a Combat Form victim is still alive and conscious, occasionally able to regain partial control for a while. The Infection Form is still visible from the outside, but destroying it will kill the host too. Infection Forms can voluntarily abandon the host if it sustains heavy damage, and if the Infection Form itself is killed or removed forcibly, other Infection Forms can take its place and reanimate the Combat Form. Simply dismembering the CF's arms won't stop it. Large concentrations of Flood biomass releases spores that can also cause an infection; because of this, the only sure-fire way to eliminate a nest is to [[KillItWithFire burn it with highly advanced energy weapons]] or [[ThereIsNoKillLikeOverkill destroy the biomass via activating the Halo rings]].
* The Many in ''VideoGame/SystemShock2'' take over nearly the entire crews of the Von Braun and Rickenbocker. They started out as [[Franchise/{{Alien}} strange eggs on an alien planet that infect the landing party]], then become controlled human hybrids that still have enough awareness to [[ApologeticAttacker apologize]] and [[IcannotSelfTerminate beg to be killed]] before they attack, before taking on even more bizarre forms. Throughout the game, they seek to telepathically convince the protagonist to join them them against [[spoiler:[[AIIsACrapshoot the evil artificial intelligence that created them.]]]]
** They're not quite ''Alien'' copies. They exhibit a number of psychic powers which make humans want to care for and nurture the worms, show them the benefits of being part of a HiveMind and ultimately join the Many. You read the diaries of several crewmembers who embraced their change.
* The Jockeys from ''VideoGame/Left4Dead2'' take a more physical approach to this trope: They simply grab on to the survivor and push them in the desired direction until someone else comes up and knocks him off their head.
* ''VideoGame/SkiesOfArcadia'' has a fairly horrifying example: the giant roaches living under the Valuan empire occasionally hijack unfortunates who wander into their territory, from what you can see in game this involves climbing onto the victim's back, jamming limbs into each of the victim's limbs, and then puppeteering them around while using them as a mobile snack. Whether the victims are killed before they get used as meat puppets is not made clear.
* From the original ''VideoGame/SilentHill1'' we have the slug-like parasites controlling the puppet nurses and doctors. [[AllTHereInTheManual The Book of Forgotten Memories]] indicates said monsters are not product of Alessa's tortured mind but the actual Alchemilla staff turned into mindless drones by her hatred of hospitals.
** Later, one such parasite takes control of [[spoiler:Cybil]] - cue boss fight. Whether Harry saves her or not depends on the player finding the [[http://silenthill.wikia.com/wiki/Aglaophotis Aglaophotis]] earlier in the hospital.
* ''VideoGame/{{Pikmin}}'' has them, as does its sequel but they're different. In the first, there are mushroom enemies that can take control of your Pikmin (complete with milky white Parasect eyes) and they'll attack you and your swarm. In the second game, there's a species of Pikmin that is parasitic that infects Bulborbs. After killing the leader of this troupe, you can whistle at the babies and control them like any other Pikmin. They're immune to all obstacles and have average speed and strength making them very useful. If you can ignore the FridgeHorror of exactly what that cute little Pikmin did to that adorable Bulborb baby.
* Glowworms in ''VideoGame/{{Limbo}}'', which shoot down from the ceiling and burrow into your head as you run underneath and force you to run continuously in one direction until you hit a source of light which turns them around. They're unavoidable and merely have to be dealt with until you can get to another creature which rips them off your head.
* Pisacas in ''VideoGame/ShinMegamiTensei''.
** [[TheDragon Sukuna-Hikona]] in ''VideoGame/RaidouKuzunohaVsTheSoullessArmy''. Made worse by the fact [[spoiler: he's driving the corpse of General Munakata]].
** And the Hiruko in the same game, [[spoiler: once they reach Red Cape stage]].
* In ''VideoGame/DeathSpank'', the Mind Barnacles that he helps spread are clearly examples of this trope but the main character helps them spread due to them offering him a quest. Plus they would bring World Peace by infecting all living things with Mind Barnacles!
* Inverted in ''VideoGame/SidMeiersAlphaCentauri''. The planet hosts mindworms who can do nasty things to humans (they are the equivalent to barbarian units in CIV games), but can be captured and utilized as military units under the right circumstances. Rather ironic to have a huge mass of alien worms being controlled by a human colonist.
* ''VideoGame/TeamFortress2'' gives a ShoutOut to the brain slugs of ''WesternAnimation/{{Futurama}}'' by having one as a wearable hat for the Pyro. It's a LawyerFriendlyCameo, so it [[http://wiki.teamfortress.com/wiki/Triboniophorus_Tyrannus looks a little different.]] According to the description, it doesn't control Pyro so much as agree with him wholeheartedly that everything should burn.
* The description for Gust's hat in ''VideoGame/HyperdimensionNeptuniaMk2'' says that the hat might actually be Gust and that it's controlling a little girl.
* For a three-part StoryArc in ''VideoGame/KidIcarusUprising'', [[spoiler:a parasite called the Chaos Kin becomes the villain and takes over [[GodOfGood Palutena]] and her army while feeding off her soul.]]
* A recent update to the [=iOS=] game ''Plague Inc.'' (similar to ''VideoGame/{{Pandemic}}'') adds the "Neurax Worm" special type of plague. Unlike all other types of plagues, the worm's goal is total domination (i.e. infection) of all humanity, not its destruction. As such, it's only necessary to infect everyone, not kill them. The image of the plague also changes from a Petri dish to a worm sitting on a brain with tendrils extending inside it. The worm seems almost intelligent in its symptoms, such as causing people to fly to a specific country in order to infect it, even if that country has closed off its airports (or has no airports). Another symptom involves violent attacks against anyone who isn't infected (yes, turning the game into a ZombieApocalypse) and active attempts to stop cure research. Like all other plague types, it's also capable of infecting animals but seems to have only limited control over them. The starting blurb mentions that the worm has been dormant for millennia only to be uncovered by excavation. Additional news mention people worshiping the worm and governments legalizing Neurax communities.
* The Mollusk Launcher in ''VideoGame/SaintsRowTheThird'' launches mind controlling octopi that cause their host to start attacking everything in sight as they eat their brain.
* Late in ''VideoGame/TheBureauXCOMDeclassified'', it's revealed that [[spoiler:Carter has been under the control of an Ethereal all this time, explaining the third-person perspective (he's actually floating behind and above Carter with energy tentacles controlling him). After Carter finds out, he forces the Ethereal out, resulting in the being bonding with one of three other characters, which will affect the ending. This is also Origin's... well, SuperheroOrigin. He had another Ethereal controlling him until he figured out how to enslave it]].
* The Squirg of ''VideoGame/WildStar'' are adorable octopus-like critters... who latch onto critter's heads and takeover their brain waves.
* ''VideoGame/TheBizarreAdventuresOfWoodruffAndTheSchnibble'': The Beast, who controls the Bigwig.
* The third game in the ''VideoGame/DontEscape'' series has [[spoiler:the crystal itself, which grows inside the player's body and, while they sleep, makes them kill all their crew members.]]
* ''VideoGame/MegaManX2'' has the Pararoid S-38 which infests and controls large destroyed machines and serves as a stage miniboss, and the Pararoid V-1 which hops onto Mega Man's back and forces him to repeatedly shoot, jump, or dash until he shakes it off.
* In ''VideoGame/MetalGearSolidVThePhantomPain'', whenever the aptly named [[BossInMookClothing SKULLs Parasite Unit]] shows up, any regular soldiers in the area (except Snake, for some reason) are infected by the parasites and turned into shambling zombies. These soldiers can still be sent to Mother Base to join Diamond Dogs if you knock them out and extract them, so apparently the infection isn't permanent.
** An even darker example occurs during the mission ''Shining Lights, Even In Death'', where everyone on Mother Base's quarantine platform becomes infected with a new strain of the fatal vocal cord parasites. The infected soldiers are compelled to go outside and emit pheromones that smell like fruit, which would attract birds to feed on them, ingesting the parasites and spreading them to the rest of the world. These parasites are directly compared to the RealLife parasites ''Leucochloridium paradoxum'', which does something similar to snails.
--> '''Diamond Dogs Soldier:''' I did it, Boss... I'm no snail.
* In ''VideoGame/{{Stellaris}}'', there is one Fungoid race that is explicitly a mammalian creature infested by fungal growths; the fungus is the sentient species, the mammal is just a platform.
* Planet Aether in ''VideoGame/MetroidPrime2Echoes'' was split in two dimensions, the default light world and a sinister dark world. The Dark Aether denizens, the Ing, have the ability to possess other creatures, gaining increased strength from the symbiosis. In fact, they require a host to survive on Aether for any extended period of time.
* According to ''VideoGame/CultistSimulator'', humanity lost the "Second Worm War" because the worms learned to work people from inside.

[[folder:Web Comics]]
* Downplayed in ''Webcomic/{{Ayuri}}'', where Fenna's species use non-sapient hosts.
* The Hat, an ugly parasitic hat from ''Webcomic/StickmanAndCube''. It eats people's heads, too.
* In ''Webcomic/GirlGenius'', the slaver wasps are themselves tools of a malevolent [[MadScientist Spark]] known as the Other. Also notable in that ''no'' DeusExMachina has surfaced; [[MercyKill death]] is still the only cure for the slaver-infected.
** Well, probably. [[spoiler: Agatha's locket is suppressing her [[GrandTheftMe psychic possession]] by The Other; it [[FanWank might work]] against the Slaver Wasps, as well.]] Of course, since there's only one of it...
*** The new generation leaves its hosts normal people who can be commanded by the right voice at any time. [[spoiler:Klaus Wulfenbach]] seems to be okay after being infected. Shambling zombies [[spoiler:[[http://www.girlgeniusonline.com/comic.php?date=20110330 ended up as a mere distraction]] from the [[http://www.girlgeniusonline.com/comic.php?date=20060317 far more insidious]] threat]].
** One possibly fictional in-universe story suggested that the Heterodyne boys made a device that could extract slaver wasps. No-one really believes that it could have worked though.
** More recently, Tarvek has [[spoiler: developed a formula which he thinks will render the imbiber immune to being wasped. Whether this actually works remains to be seen, and it won't do much good for those already infected]].
** After the TimeSkip, it is said Gilgamesh (to whom Tarvek gave his notes) has inoculated all of the Wulfenbach soldiers and agents against slaver wasps.
* The slugs in ''Webcomic/JumpLeads''. [[spoiler: They are killable by contact with silks. A real irony for working class soldier that join the army to not wear silk clothes, which is a best mean of defense.]]
* ''Webcomic/ElGoonishShive'' has Sirleck ([[http://www.egscomics.com/index.php?id=1078 this thing]]), a former human who achieved immortality by jumping from host to host.
* Prior to the start of ''Webcomic/{{Intragalactic}}'', Piper's brain was eaten by a Brainworm. However, the worm inherited her memories and personalities and has essentially continued her life for her, making her corpse walk and talk for it. In fact the only apparent changes death has brought about in Piper are a deathly pallor and a guilt complex (from killing the original Piper).
* ''Webcomic/GunnerkriggCourt'' has Whitelegs.
** And Reynardine.
* In ''Webcomic/GeneralProtectionFault'', it is revealed that Fred and other slime molds have the ability to control people's movements and speech. It is heavily implied that [[spoiler:the enemy aliens from the Nega-Verse are also slime Molds, since they controlled Nega-Dwayne and Nega-Butch to weaken the humans through infighting]].
** And now [[spoiler:they're invading in the main universe, having taken over Agent #18 and - it appears - Nega-Nick...]]
* The Fixits in ''Webcomic/TheMansionOfE'' are hat-shaped critters who are able to control their "wearer".
* In ''Webcomic/TowerOfGod'', [[spoiler: Yihwa Yeon]] gets taken over by a green parasite and attacks Prince. It isn't made any less disgusting when the parasite is as big as a torso, entering orally and the entire affair looks rather suggestive.
* ''Webcomic/BasketsOfGuts'': WordOfGod mentioned that [[MushroomMan myconids]] can control those who are infected with their spores, and they're well aware of this fact.
* Miesti in ''Webcomic/{{Galaxion}}''.

[[folder:Web Original]]
* ''JohnDiesAtTheEnd''; more apparent in the [[http://www.johndiesattheend.com/jdate2/intro.html sequel.]]
* The Wormbrains from WebOriginal/{{Mortasheen}} are an entire class of creature that does this, with the parasitic worms serving as the creature's mind. They come in many [[SarcasmMode "lovely"]] forms like [[http://www.bogleech.com/mortasheen/cestoid.htm this]], [[http://www.bogleech.com/mortasheen/proglapse.htm this]], [[http://www.bogleech.com/mortasheen/manticoil.htm this]], and [[http://www.bogleech.com/mortasheen/squirminator.htm this]].
* In the ''WebVideo/TransolarGalactica'' episode "The Invasion", the crew of the ''Transolar'' attempts to wipe out the human colonists on Lazariz because they've been taken over by "mind slugs". Unfortunately, it turns out that Samson [[spoiler:made them up to "look cool in front of the captain".]]
* The {{Creepypasta}} "[[http://www.creepypasta.com/psychosis/ Psychosis]]" follows a man who starts going crazy and thinking that everybody but him has been abducted/killed and replaced by an EldritchAbomination impersonating them. He's totally wrong of course. Everybody but him has ''actually'' been taken over by Puppeteer Parasites, put into an AndIMustScream situation where they want to help the protagonist but can't.

[[folder:Western Animation]]
* Parodied on ''WesternAnimation/{{Futurama}}'', wherein the efforts of the "brain slugs" to acquire new hosts are always blatantly transparent, as in one episode where a controlled Hermes Conrad informs the crew that their next delivery is to the Brain Slug Homeworld, where their orders are to "just stand around not wearing a helmet". The Brain Slugs themselves are pretty obvious too, being [[UglyCute weirdly cute]] green blobs with big eyes attached to the head of the controlled individual.
** It is implied that the brain slugs not only control but slowly ''digest'' the host's brain too, or at least feed on the host's brain waves. One of the brain slugs tried to infest Fry's brain, but [[YourBrainWontBeMuchOfAMeal died of starvation]]. [[spoiler: Though this is mainly because Fry has abnormal brain waves that make him immune to mind-related shenanigans.]]
* The Vodun from ''[[WesternAnimation/RoswellConspiracies Roswell Conspiracies: Aliens, Myths and Legends]]'' are puppeteer parasites that can only control corpses. They have been trying to upgrade to living bodies for years but they've had trouble since infesting a living being involves a BattleInTheCenterOfTheMind between parasite and host that usually leaves both parties permanently brain-dead.
* The Xenocytes from ''WesternAnimation/Ben10AlienForce'' were a species of alien parasite engineered by the [[BigBad Highbreed]]. They latch onto a host and slowly overwrite their DNA, turning them into monstrous slaves of the Highbreed called [=DNAliens=].
* The Brainteasers from ''WesternAnimation/DarkwingDuck'' qualify, and since they look like hats, they go undetected for quite some time.
* The Racing Bugs from ''WesternAnimation/JimmyTwoShoes'' replace their hosts GhostInTheMachine and use the vessels to race. They're mainly harmless, and actually give their hosts super speed. The only reason they're frowned upon is that they're [[{{Squick}} fleas inside your head.]]
* ''WesternAnimation/CourageTheCowardlyDog'' has Mastafa al Bacterius in his first appearance, where he was a worm with a spacesuit and jetpack who takes control of Muriel's body before personally trying to take Courage out.
* In the ''WesternAnimation/AdventureTime'' episode "Little Dude", Finn's hat comes to life and becomes this, with the ability to increase the strength of its current host.
* Rip's ''[[ItMakesSenseInContext shorts]]'' become this in ''WesternAnimation/TheRippingFriends'' after enduring the most ridiculous origin imaginable. It can control a host by riding up on them and ultimately takes over [[CaptainErsatz Pooper]] [[Franchise/{{Superman}} Man]].
* Played for laughs in ''WesternAnimation/RickAndMorty'', where the sinister alien HiveMind controlling people's wills through green slime is revealed a couple minutes into the episode to be Rick's ex, Unity. Summer initially wants to free the planet it's controlling and is horrified that Rick just gets back together with it, until she discovers what the people it's controlling [[TheEvilsOfFreeWill are like otherwise]]. She still thinks they shouldn't be together, but because ''Rick'' is a bad influence on ''it'' (and by extension, everyone on the planet).
* Episode "Ghostworld" of ''WesternAnimation/TheRealGhostbusters'' has a similar premise mix with DemonicPossession. A group of ghosts take control of the Ghostbusters one by one after they go to a ghost-themed amusement park. At first only Ray and Slimmer want to go (as they are the more child-like) but after the ghosts take control of them they trick the other ghostbusters in going.
* An episode of ''WesternAnimation/MenInBlack'' has a parasitic alien plant doing this after successfully passing the controls in the Men In Black's customs checkpoint, taking control of most of the MIB except for Kay, Jay and Elle.

[[folder:Real Life]]
* ''[[http://en.wikipedia.org/wiki/Toxoplasmosis Toxoplasmosis]]'' is a very real parasitic infection (caused by the protozoan toxoplasma gondii)
** In humans, it is now believed that infestation with the parasite may change the personality of infected humans, making men more aggressive and less fearful, while making women kinder and more promiscuous. It may also increase the chances of getting into a car accident, and there is some evidence (although far from conclusive) that it may be linked to schizophrenia and increased risk of suicide. It is suspected that between 30 and 60 percent of the population of the world is infected, albeit asymptomatic.
** The same parasite typically infects rodents and alters their brain chemistry significantly-incidentally, this is why it changes human personalities. The alterations it makes are actually necessary to reproduce: it can only infect rats and mice, but it needs cats innards to breed, so it changes the brain chemistry around to that its host is attracted to the scent of cat, rather than repelled as normal. Then it gets eaten and the whole process starts again when the cats defecates.
* [[https://en.wikipedia.org/wiki/Nematomorpha Horsehair Worms]] infect grasshoppers and praying mantises while young, then influence their host to go to the water when they are ready to [[ChestBurster rip through its chest]] and begin their free-living existence. [[http://www.youtube.com/watch?v=D7r1S6-op8E This is a cricket, but same difference]].
* A species of fluke infects snails, then extends its eggsack into the antenna of the host, then causes the snail to position itself so that its antenna where a bird can easily see it. The bird then eats the infested antenna (swollen to look like a worm) and becomes infected. [[http://www.youtube.com/watch?v=EWB_COSUXMw See it here!]]
* One species of parasite causes ants to crawl up to the top of a plant, bite the edge of a leaf, and just sit there. This greatly increases the chance they will be eaten, allowing the parasite to spread.
* There are 400 documented species of fungus within the genus ''Cordyceps'' -- each specific to one species of insect -- which infest the hosts and then force them to chill out somewhere where they can catch the breeze and never move again for the rest of their lives, so that the fungus can grow out of their heads and spread more spores to start all over again. Another one infects flies and makes them grip a blade of grass and flap their wings until they die of exhaustion, taking a slightly more active role in spore-spreading.
*** ''[[http://www.youtube.com/watch?v=XuKjBIBBAL8 Cordyceps unilateralis]]'' targets ants, forcing its ant host to climb to a position that overlooks their own nest, so that the entire nest will be infected when the ant dies and starts scattering spores. However, the ants themselves have evolved a mechanism in response to this, so that any time an ant starts showing symptoms of infection the rest of the ants will carry it a long way away so it can die without threatening the nest. This must be the plot for at least five sci-fi horror movies and [[VideoGame/TheLastOfus definitely one video game]].
* The mushroom involved in the example of Parasect of ''Franchise/{{Pokemon}}'', above, was explicitly named to be ''[[http://en.wikipedia.org/wiki/Ophiocordyceps_sinensis Ophiocordyceps sinensis]]'', which is indeed treasured as a medical mushroom in east Asia.
* Fungi residing in the human digestive tract can make their hosts feel very uncomfortable unless they eat enough sweets to satisfy the fungi. And you can get infected by simply eating infested bread...
* There's a species of barnacle of the genus ''Sacculina'' that infects female crabs and grows tentacles into its brain. It then lays eggs in the crab's egg sac, which swells up with baby zombie-making barnacles to infect other crabs with. And if it gets into a male crab, [[GenderBender it turns him into a female crab]].
* Xenos vesparum is a parasite that lives in wasps. It enters a young wasp as a larvae and grows while the wasp stays small and becomes infertile. When Xenos mating season comes, it forces its host to fly to a special place, where the Xenos in this area meet. Now the males kill and leave their hosts and mate with the females. The female now forces its host into hibernation and in the spring flies it to a wasp colony where the parasite larvae can find their own hosts. Then the female kills its host. And nobody knows how they do it.
* The phorid fly infects fire ants by laying its eggs into their thorax. During development, the larva moves to the ant's head and directs the ant to move a safe distance away from its colony while simultaneously devouring its brain. Using digestive enzymes to separate the head from the body, the larva continues to pupate within the ant's decapitated noggin until its ready to emerge from its grisly cradle and continue the cycle anew. They are also responsible for the mysterious Colony Collapse Disorder (CCD) among honey bees.
* A certain species of wasps uses caterpillars as [[ChestBurster living nurseries]]. However, one of the eggs contains a larvae that never reaches maturity. Instead, it turns the caterpillar into a zombie, and when its siblings pupate, the wasp larvae uses the caterpillar as an undead guardian which violently lashes out at predators.
* [[http://en.wikipedia.org/wiki/Phronima The pram bug,]] ''Phronima spp.'' The females of these deep-sea crustaceans lay their eggs inside of something (usually a type of sea squirt known as a salp), and pushes the salp around like a baby carriage. They were once [[WordOfDante thought to be]] the inspiration for the Aliens in the ''Franchise/Alien'' franchise, although WordOfGod states that that's not true.
* The Crypt-Keeper Wasp takes this to the next level by the virtue of being a [[https://en.wikipedia.org/wiki/Hyperparasite hyperparasite]] i.e a parasite whose host is another parasite. Specifically, the Crypt-Keeper Wasp attacks the Gall Wasp, a type of wasp that targets trees and forces them to create hollow chambers rich in nutrients where the insect deposits its larvae. After infecting a host, the Crypt Keeper larva makes its victim drill a hole that's too small for its own escape and once the large wasp is trapped inside the wedge, the insidious Crypt Keeper eats its host from the inside out and burst out of the gall wasp's forehead into the world.