->"Jesse is dead! You have to remember that when you see him, you're not looking at your friend. You're looking at the thing that killed him."\\
-- '''Giles''', ''{{Buffy The Vampire Slayer}}''

->"I come from the Net. Infecting systems, people, and cities, to this place, '''Mega'''frame: my domain. My format, Virus: To corrupt and conquer!"\\
-- '''Megabyte''', ''{{ReBoot}}''

The Virus comes in many forms in many genres. Simply put, The Virus turns people [[YouWillBeAssimilated into itself or into entities subservient to itself.]] The transformation is both [[{{Brainwashed}} mental]] and [[ViralTransformation physical]]. The converted will have unflagging loyalty and be instantly ready to commence villainous actions.

If the converted still resemble their previous selves, they will use their personal knowledge to prevent their former loved ones from doing them harm, or from trying to [[IKnowYouAreInThereSomewhereFight get them back.]] Despite the [[GrandTheftMe body snatching]], if The Virus is only able to crudely mimic human behavior it may lead to a GlamourFailure. If The Virus mutates their host to the point where they are almost unrecognizeable, expect it to do the same to environments. This tends to lead to the WombLevel and OrganicTechnology.

How much of the former person is left after infection depends on the series, as does whether or not the process is [[OurVampiresAreDifferent reversible.]] It also depends on whether it's a main character or not, they can sometimes use The Virus' powers against it with enough HeroicWillpower (a property more typical of TheCorruption). If The Virus is sentient, then more often than not it is also a HiveMind with a HiveQueen directing it.

Stories of yesteryear often tied this symbolically with the RedScare; nowadays if it represents something, it's TheHeartless. The lowest common denominator for man to sink to, susceptible when one lets their own [[TheDarkSide Dark Side]] take over -- and it takes people around them down too.

Often how humans [[WasOnceAMan become something much, much more horrible.]]

Sometimes overlaps with BodyHorror in cases where the host enters a zombie-like state before being completely consumed. Compare ViralTransformation, where a similar change ''does not'' cause a FaceHeelTurn. See also ThePuppetMasters, FaceFullOfAlienWingWong and FisherKingdom.

----
[[foldercontrol]]

!!Examples

[[folder:Anime & Manga]]
* The Invaders from the {{anime}} ''{{Gatekeepers}}'' and its dark sequel, ''Gatekeepers 21''.
* ''VenusVersusVirus'': The Virus is actually called that; it changes humans into demons.
* ''MermaidMelodyPichiPichiPitch'' has Yuuri's hypnotic piano playing.
* The Festum in ''FafnerInTheAzureDeadAggressor''.
* In one chapter of ''TheKurosagiCorpseDeliveryService'', a real-life virus that infects snails begins to infect humans instead, with art that puts the horror back in BodyHorror.
* This happens to ''entire planets'' in the ''[[{{Gradius}} Salamander]]'' OVA.
* ''HigurashiNoNakuKoroNi'' takes this in a somewhat weirdly literal direction with [[spoiler:Hinamizawa Syndrome. Once someone's case has been aggravated, you really can't bring them back easily. [[PowerOfFriendship Although there are exceptions]].]]
* The Dark Spore in ''DigimonAdventure02'', though its effects tend to be somewhat MoreThanMindControl.
* ''BlueDrop'' has a somewhat lesser example. The second manga, ''Tenshi no Bokura'', implies that any human female sexually exposed to the OneGenderRace Arume (a species of alien lesbians who reproduce by cloning) becomes somehow psychologically incapable of loving a man, possibly due to special pheremones (a form of chemical warfare?). The implications for both species, as well as the results for society, are truly [[NightmareFuel horrific]].
* DG Cells from ''GGundam'', proving that the only thing worse than zombies are [[NinjaPirateZombieRobot cyborg zombies]]. With [[HumongousMecha giant robots]].
* The anime of the series ''LeChevalierDEon'' has this trope. In that people being controlled by the Psalms turn into "ghouls" who bleed silvery blood and their flesh is all gross looking. They don't seem to have control over their bodies, though in typical fashion the "infected" may have some dying words such as "kill me" to mutter.
* The series ''RedGarden'' has this as well. This troper has yet to watch the series to the end and thus doesn't know what causes it... but in the first episodes those affected by "the virus" appear to be superhuman. One of them also walks like a dog.
* The Spiral in ''{{Uzumaki}}''. [[HighOctaneNightmareFuel I'm not going to describe it any further.]]
[[/folder]]

[[folder:Comics]]
* The OMAC from TheDCU are complex nanomachines that hide in a person's body until they are kickstarted through a command by Brother I. They proceed to take over the inhabitant's body and turn him into one of the electric blue, one-eyed killing machines. Ironically, they were spread through tainted flu shots.
* For a MarvelUniverse equivalent, during the "Operation Zero Tolerance" arc, Bastion turned certain people into "Omega Sentinels" by abducting them, filling them with nano- and cybernetics, and placing a sleeper program in them that would activate in the presence of mutants.
* The comic book series ''{{Powers}}'' had an arc that revolved around a dangerous and addictive superpower, ([[DrugsAreBad can anyone say drug addiction allegory?]]) that was spread between people, infecting new users.
* The "Legion of the Damned" arc in DC's post-''Zero Hour'' ''LegionOfSuperHeroes'' features the Blight, which ravages the [[TheFederation United Planets]] and takes over most of the Legion before the remaining Legionnaires manage to purge it.
* In {{DCU}}'s ''FinalCrisis'', {{Big Bad}} Darkseid uses the [[BrownNote Anti-Life Equation]] this way, bringing Earth under his control, and transforming some of the heroes into his monsterous servents.
** Ironically, Checkmate uses the millions of people infected with OMAC nanotechnology left over from the [[InfiniteCrisis last crisis]] in order to fight against the Anti-Life Justifiers, making this a Virus versus Virus situation.
[[/folder]]

[[folder:Films]]
* Many classic vampire and werewolf movies had those bitten (or killed) by the monster becoming monsters themselves.
* Same goes for a lot of ZombieApocalypse movies as well: "The people it kills get up and kill!"
** Except that Romero zombies, at least, get up and kill simply because they are dead, not because they have been specifically infected.
* ''The Thing'' (from the 1982 John Carpenter movie, and the story ''Who Goes There?'' which inspired it) is the literal embodiment of The Virus -- a fiendish microorganism that replaces the victim's cellular structure with itself. The Thing also displays the ability to perfectly mimic any living thing -- until it's threatened, at which point it flips out and [[OneWingedAngel begins sprouting tentacles, giant toothy mouths, etc.]]
* Agent Smith in ''TheMatrix'' sequels. After Neo tried to delete him, he comes back and now can copy himself into other people. Ironic, given that he was disgusted by human race and called them a virus in the first movie beforehand.
** Also, for symbolism points, his sunglasses changed after his resurrection. Originally they were square, and now they're slightly more rounded, and have the general shape of a protein capsule of most viruses.
* The 2008 horror movie ''Quarantine'' (and the movie it was a remake of, ''REC'') picked up on the appropriateness of rabies as an example of The Virus by making a mutated version the film's threat.
** In the original ''REC'' it was suggested that The Virus has a more... supernatural origin.
* As the name implies, the antagonist from creepy 1999 film ''Virus''. A transmission from space takes control of a (seagoing) ship's computers and begins building something. When the heroes ask the program what it wants, it replies with a list of ''body parts''.
* The alien in ''{{Slither}}'', which spreads through parasites that turn hosts into drones for the HiveQueen, controlled through a HiveMind.
[[/folder]]

[[folder:Literature]]
* The [[OneGenderRace hermaphroditic eponymous race]] in Storm Constantine's ''Wraeththu'' books change young human men into Wraeththu by transfusing them with Wraeththu blood, then stabilize the transformation via [[FaceFullOfAlienWingWong sex]].
* A unique example from CharlesStross' SF novel ''Singularity Sky'': Mimes. Mimes who reproduce themselves by hitting humans in the face with pies -- the pies are full of nanotech that reformats the human into a new Mime, complete with more pies. Lucky for those being pursued by Mimes, they are afflicted with the sort of tics you'd expect, such as occasionally being trapped inside an invisible box or having to walk against the wind.
* Stross also created "Curious Yellow" in the novel ''Glasshouse''. CY was a digital virus that was capable of controlling people and removed their memories (as well as computer records) of... something. What no one ever found out, even after the long, brutal war to contain and defeat The Virus.
* A particularly unusual example shows up in Philip K. Dick's novel ''The Three Stigmata of Palmer Eldritch''. The titular character distributes an [[LotusEaterMachine exceptionally trippy drug]] with the side effect of causing the users to think more like he does than they used to -- and also causes them to spontaneously develop Palmer's "three stigmata", which are artificial eyes, a metal jaw, and a replacement arm.
* One of the creepiest examples ever is Philip K. Dick's short story ''Upon the Dull Earth''. A weird necrophiliac woman attempts a bizarre experiment to speak to the "angels" who supernaturally rule the Earth, which fails and claims her life. Her grieving boyfriend bargains with the angels to bring her back in a DealWithTheDevil. Unfortunately the angels screw up when doing so -- the girl comes back, but only by hijacking another person's body, taking over her sister's body and physically transforming it into her own. The angels seem unable to stop this process, either -- soon everyone in the world begins spontaneously transforming into a duplicate of the girl. Madness and horror ensues.
* Another [[{{Squick}} Squicky]] example occurs in ''Spiral'', the first sequel to ''Ring''. Any time a woman watches the cursed videotape (or any of it's derivatives), whilst ovulating, they become pregnant with a clone of Sadako, which develops to birth in a week, leaving the host to die.
* The Solanum virus from the Max Brooks book ''{{World War Z}}''. Lethally toxic to all animal life if ingested. Kills and reanimates humans bitten or scratched by the infected or exposed to their bodily fluids, and can potentiality reanimate infected people who die from other causes while the virus is incubating. Does NOT raise long-dead people from their graves.
* The Conjoiners, a HiveMind culture in AlastairReynolds's works, are actually the good guys in a number of stories. They started out as a handful of scientists who linked their minds as an experiment and subsequently released a virus to assimilate more minds into the collective, but later their goal became simply to survive. They consider conscripting their enemies a more human alternative to killing them.
* In Steven Hall's ''The Raw Shark Texts'', Victorian "gentleman scientist" Mycroft Ward gradually becomes this. He cheats death by transferring his personality into a younger man, and this new body cheats it again by sharing knowledge with a second person. It all [[GoneHorriblyWrong goes bad]] when the increased self-preservation instinct causes him to search out more and more hosts.
* Faction Paradox in the ''DoctorWho'' novels had "Faction biodata", which they could inject into such things as regenerating Time Lords or pure life energy creatures melding with a planet's ecosystem, turning their hapless victim into a tool of the Faction. This would normally be ''bad''. It becomes '''horrifically bad''' when the infected Time Lord in ''Interference'' is [[spoiler: the Doctor]].
[[/folder]]

[[folder:Live Action TV]]
* The vampires from ''{{Buffy the Vampire Slayer}}''. ''Buffy'' vampires have their previous selves' souls replaced with a demon (though it can be [[{{Angel}} retreived later by a spell]]). However, [[OurSoulsAreDifferent the series establishes that the soul is just one's conscience]], and the vampires retain their memories, the vampire ends up being a twist on the original persons soul. Some personality traits remain in the vampire:
-->'''Willow:''' It's horrible! That's me as a vampire? I'm so evil and... skanky. And I think I'm kinda gay.\\
'''Buffy:''' Willow, just remember, a vampire's personality has nothing to do with the person it was.\\
'''Angel:''' Well, actually... ''(sees Buffy's expression)'' ... That's a good point.
** In the episode "Bad Eggs", students participating in a health project raise eggs as if they were children. The eggs end up hatching and the demons inside of them take control of whoever was supposed to take care of them. All of the egg-demons are controlled by the "mother" demon below the school.
** This is actually a reversion to the original vampire legends in Eastern Europe, in which spirits called ''upir'', which are supposed to be simple psychopomps (escorters of the dead to the afterlife), glom into the now-soulless bodies and walk about in search of fun.
* The Borg from ''StarTrek''.
* The Cybermen of ''DoctorWho'', who were arguably the inspiration for the Borg.
** The "Empty Child" in the new ''DoctorWho'' series (from the episodes "The Empty Child" and "The Doctor Dances") was [[spoiler: a little boy raised from the dead by alien medical {{nanomachines}} that had no clue how to rebuild humans. Anytime he touched someone, the nanomachines would reprogram them to the way they thought all humans should be -- down to the gasmask and injuries the boy had when they found him.]]
** And the Primords in ''Inferno''. If they even touch you -- hell, if you touch that green stuff for even a fraction of a second -- it's only a matter of time before you become a mindless Primord.
** [[spoiler:The Flood]] from "The Waters of Mars", [[spoiler:literally a (water-borne) virus]].
** The ''Bane'' fizzy drink from ''TheSarahJaneAdventures'' spin-off of ''Doctor Who''.
* The demonic virus from the ''{{Supernatural}}'' episode "Croatoan". No explanation (as of yet) why it didn't affect Sam but affected everyone else who was exposed to it.
** The revelation at the end of season two that [[spoiler:Azazel infected Sam with his own blood the night of the fire]] more than likely covers it.
* Inverted in ''StargateAtlantis'', where the "good guys" invent a virus that turns enemy Wraith into docile, submissive humans. Of course, [[WhatTheHellHero they really don't go about this in the best way]], and things quickly go downhill.
* The Orphenochs from ''KamenRiderFaiz''.
* A key trait of Dezumzorya, the BigBad of ''[[SuperSentai Bakuryu Sentai Abaranger]]''. It combines physical infection with MoreThanMindControl to great effect.
* The fungus from ''{{Primeval}}'' takes root in human skin, eventually taking over the brain and transforming the host into a bizarre killer fungus creature.
* Random Virus in AceLightning: former Lightning Knight turned [[AIIsACrapshoot mentally unstable cyborg]]. Interetsing in that his old self is still there - it's just that he [[JekyllAndHyde can't help switching between them on a regular basis]].
[[/folder]]

[[folder:Theater]]
* The opera ''Help, Help, The Globolinks!'' has [[AlienInvasion invading aliens]] called Globolinks whose only known weakness is music. Humans touched by Globolinks are gradually transformed into Globolinks, first losing the ability to speak human language.
[[/folder]]

[[folder:Tabletop Games]]
* ''[[DungeonsAndDragons Dungeons & Dragons]]'' has the olive slime, yellow musk creeper, and probably other monsters of this kind. One prominent example is the vargouille; it's a relatively low-level monster (Challenge Rating 2) that reproduces by "kissing" members of another species. Unless this kiss is cured with an appropriate spell, over 24 hours, the victim's hair falls out, their head becomes more wrinkly, the ears grow and become wings, and eventually, the head ''separates from the body'' and becomes another vargouille. It was even more creepy in the first edition, when the separated head would ''still have a variety of internal organs attached, dangling down from the neck''.
** Also, the chaos beast could turn mortals into other chaos beasts. The Slaads can infect someone with their bites or their claws, placing Slaad eggs inside of the person, who'll eventually eat their way out, making new slaads.
** Mind Seed is one of the most insidious psionic powers in 3.5. Implant someone with a Mind Seed and it will slowly reshape the victim's mind -- against their will -- into a mental replica of the psion at the time the power was used. Though the resulting personality will still have their own free will, the fact that it now shares the goals of the psion makes it incredibly effective.
* ''Elder Evils'', a sourcebook on all things CosmicHorror, also gives this power to SealedEvilInACan Father Lymic, with the Brood created by him given a fraction of his ElementalPowers over ice. His goal is to ultimately corrupt the world, turning it into a SingleBiomePlanet of snow and darkness. Yeah, he's scary.
* ''{{GURPS}}'' has, at the least, Riders (from ''{{GURPS}} Aliens'') and Valkryies (from ''{{GURPS}} Traveller: Alien Races 4'' [I think it was ''4'']). Note that these are both ostensibly science-fiction (rather than fantasy or magical) species.
** 4th Ed Ultratech has a metamorphosis virus that can be weaponized into either this or a version that turns everyone into random things, which can be much worse.
* In ''{{Warhammer 40000}}'', you have the insidious powers of [[CosmicHorror Chaos]], which can quite effectively turn the open mind into a willing cultist and a traitor to mankind.
** You also have the insidious [[HordeOfAlienLocusts Tyranid]] [[ExtremeOmnivore swarms]], the insidious [[FaceFullOfAlienWingWong Genestealer]] cults, the insidious [[ScaryDogmaticAliens Tau]] propagandists/brainwashers, the insidious [[OmnicidalManiac Necron]] [[HalfHumanHybrid Pariah]] harvest, etc., etc., etc. Rarely is any given conflict zone in ''40K'' NOT subject to some form of The Virus. Let's just say that in this universe, GeneralRipper typically has the right idea.
** And of course, there's the dreaded Obliterator virus, which turns you into [[HighOctaneNightmareFuel something truly horrific]]. The first tip that something horrible is going on is when you realise that you're spontaneously generating ammunition for your gun, which is becoming gradually more attached to your hand. From here, it's only a short trip to the point where you're an out-and-out psycho who can absorb guns, then create them again fused to your flesh.
*** Am I the only one who thinks that sounds [[CursedwithAwesome pretty damn awesome]] compared to the fates of some Chaos cultists, especially those who fail (think living flesh bag of pain and get worse). Wouldn't mind being an Obliterator at all if not for the whole going insane bit.
* Another electronic example is The Virus in ''{{Traveller}}: The New Era'', originally designed as a weapon for shutting down the navigation systems of enemy warships in order to end the war without further bloodshed. [[FinaglesLaw Unfortunately]] the version that was prematurely unleashed when the research station working on it was attacked would shut down ''every'' computer in the vicinity through means unexplained (though heavily implied to be [[PsychicPowers psionic in nature]]), with... ''[[KillEmAll interesting]]'' consequences if that computer happened to control (for instance) a nuclear reactor or a life-support system. Then it evolved full intelligence, [[AIIsACrapshoot which didn't improve matters.]]
* One of ''FengShui'''s many Creature Powers is "Corruption", which allows a supernatural creature to infect others with their supernatural essence, and in this way create more of their kind. Corpse factories in the ''Glimpse of the Abyss'' supplement use a variant of this to create zombies for all your ZombieApocalypse needs.
* The short-lived ''{{Nightlife}}'' horror RPG had a race of borg-like monsters that embodied The Virus trope. Surprise, surprise, they were ''called'' "the Virus".
[[/folder]]

[[folder:Video Games]]
* In the video game ''{{Prototype}}'', the character [[spoiler: Alex Mercer]] ''is'' The Virus. Under the right circumstances, The Virus gives you the powers to fly around and kill stuff with viral blades and whips and shit (as in the case of the main character); otherwise, you'll turn into a mindless, shambling, ''living'' zombie or a mutant with augmented speed and strength (as in the case of '''a lot''' of New Yorkers). It also infests warehouses ([[FridgeLogic and ONLY warehouses for some obscure reason]]) to produce beefed up mutants that are ''[[GoddamnedBats incredibly annoying]]''.
** Only annoying until you get the blade air attack, which gets them consumable in two hits. Then they become a handy and valuable biomass source.
* In ''Resistance: Fall of Man'', an alternate history first-person shooter, the aliens known as the Chimera use a mutagenic virus that causes humans to fall into a coma and undergo horrific physical mutations that turn them into Chimera soldiers. These mutated soldiers retain no trace of their former personality and are completely subservient to the elite Chimera known as Angels; in fact, Chimera soldiers die if their psychic link with the Angels is severed.
* Appears in the ''WarCraft'' series. The Lich King produces a virus which kills humans, then resurrects them as undead loyal to him. There is also a faction of Undead, the "Forsaken", who have broken free of the Lich King's control and have regained their free will.
* The Flood in the ''{{Halo}}'' franchise, which latches onto sentient life forms, hijacks their body, mutates them horribly, and, when the host is no longer usable, uses it to incubate more Flood infection forms. The infection forms even look like macroscopic bacteriophages.
** And when the Flood hijack enough bodies, they build a Gravemind; a giant, rhyming, MagnificentBastard HiveMind.
** To make it even worse, the minds and memories are assimilated, and it's possible that the living mind of the victim gets [[AssimilationPlot assimilated (in backstory said MagnificentBastard has a habbit of bragging about transhumanism and ending suffering).]]. This allows the Flood to, after a certain stage of outbreak, use any tool you can, if they can get their grubby tentacles onto it. Coupled with icky BodyHorror and the assimilation and hacking of even spaceships, this NightmareFuel isn't too much of a stretch to imagine wiping out an entire pan-galactic civilization.
* Though it involves no physical changes aside from a possible pallete swap, the Maverick Virus from the ''MegaManX'' franchise otherwise qualifies.
** And after the Maverick Virus in ''MegaManZX'' [[spoiler: Model W gained the ability to manipulate the thoughts of humans and Reploids alike. This became important for Albert's XanatosGambit .]]
* ''FinalFantasyVII'' had the Jenova cells. They started up a fairly innocuous power-boost, except in a few very specially treated individuals, who began to suffer from mad wanderlust and lose their minds. They then attempt to join up with the head of Jenova. Naturally, the main character, who was traveling all over the world for a reason he could hardly justify, based on little more than instinct, and seemed to suffer occasional but horrific mental episodes, turned out to [[spoiler:be one himself]].
** Jenova's machinations go much further than this. According to Ifalna, in her interviews with Professor Gast, Jenova first landed on the Planet and began spreading its cells like a virus, mutating the Cetra into horrible monsters under its control. It seems that Jenova itself is an entity that travels from Planet to Planet, infecting the native inhabitants and transforming them into monsters that it uses to further spread its infection around, before bringing them all back and "reuniting" itself to travel to another Planet and continue the cycle. How long it's been doing this is anyone's guess.
* The Super Mutants from the ''{{Fallout}}'' games were caused by The Virus; the first game culminated in the player destroying the transformation vats, although they could agree to be turned into a Super Mutant to achieve a NonStandardGameOver.
* ''MetroidPrime'''s Phazon is an example, but to very varying degrees, depending on the game and target.
** In ''Prime 2'', the Ing also have a tendency to take over the bodies of other creatures, both living and [[ZombieApocalypse dead]].
*** The X Parasites from ''Metroid Fusion'' are a more traditional version of this trope, as their only purpose is to infect more people.
* ''MassEffect'' includes the [[spoiler:Thorian, which is a plant-like entity that uses spores to mentally control people through pain.]] Also, there's [[spoiler: Sovereign, a Reaper which controls the minds of its victims through a process known as "indoctrination." People controlled by Sovereign can only be saved by killing them.]] Both cases also involve instances where people choose to [[DrivenToSuicide overcome the mind-control the only way they can.]]
* The Sands of Time in the ''{{Prince of Persia}}'' trilogy work like this. Once released, they instantly turn everything they come in contact with into a crazed EnemyToAllLivingThings (living in this case being the few lucky souls who wern't instantly transformed). Somehow, when the Prince is exposed in the third game of the series, he manages to resist instant transformation, although he does still get a SuperpoweredEvilSide.
** The Corrupted, from the sequal, are an aversion-it's pretty much their own damnn fault they're {{Eldritch Abomination}}s now
* The ''{{R-Type}}'' series eventually evolved the Bydo into something like this, although this isn't their favored modus operandi: usually, they simply evolve, replicate, and reproduce to improve themselves and strengthen their numbers, but given the opportunity, they will assume forms that are designed to infect and assimilate enemy technology and personnel. R-Type Delta had a good example of this in several of its ships and one of its MultipleEndings, and R-Type Final and R-Type Tactics/Command use this as a turning point in their respective storylines (much more the latter, with it even affecting gameplay).
* ''System Shock 2'' had the incredibly creepy Hybrids, alien worms controlling the brains of human corpses. These went on to mutate into higher alien forms. Just to make it more wrong, apparently part of the human consciousness survives the process.
* ''ResidentEvil'' is replete with these, both in the form of ''literal'' viruses, and the Las Plagas parasites.
* ''{{Knights of the Old Republic}}'' has [[http://starwars.wikia.com/wiki/Rakghoul rakghouls]], deformed mutants with infectious bites, living in the Undercity of Taris. The player character cannot be infected, but several infected NPCs are seen transforming. In some cases it can be prevented with a dose of rakghoul serum, but once the victim has actually been transformed they must be killed. Interestingly, when the player character or a party member is bitten, they can be poisoned and take standard poison damage, and there is an instance where you save an NPC and he has been bitten and poisoned, but no one comments on this. This may mean that the rakghoul disease can be avoided outright if treated immediately.
** In the comics, it was revealed that the rakghoul disease was concocted by a Sith who made a talisman that instantly transformed humans into rakghouls which he could control, getting them to use their old skills, like weaponry. Comics taking place between the movies of the original trilogy had a fallen Jedi using this talisman on various heroes, including a member of TheRemnant.
* ''{{Extermination}}'' revolved around this. The Virus would mutate and corrupt pretty much anything to do with water. The player probably would freak out about the time a puddle of water actually attacked/infected him. Getting 100% Infection and not curing it ''fast'' leads to a NonstandardGameOver where the player watches the transformation into a monster...
* The Beast subversion entity from the first ''{{Homeworld}}'' sequel certainly counts. It quite literally rips its host apart, extracts their neurons, and then sets about using them to form an organic computer network it can subsequently use to control the ship they were flying, and hence infect more vessels. The quote formerly at the top of the page comes from the initial cut-sequence describing the entity -- spoken by a poor engineer who sounds like he either wants to throw up or cry just about all the way through.
* ''Silpheed'' has [[spoiler:an entire ship -- the ship that ''refueled you about ten seconds ago'', to boot --]] get taken over by an alien virus and turns into not only an enemy alien, but also ThatOneBoss.
* The old ''Area51'' lightgun game revolves around an alien virus being unleashed and causing a ZombieApocalypse in the area. The GameOver screen shows a video of the protagonist morphing into one of the alien mutants.
* ''DeadSpace'' 's Necromorphs are unique in that only one of its forms is The Virus and it can only infect dead people. It's the task of the other Necromorphs to ensure there are dead bodies to infect.
** the Virus can somewhat infected people but only after weeks of being in contact with the source [[spoiler: or at least being around the marker]], drive them insane and kill themselves, after a few more hours the virus takes effect. The infector verson just speeds up the progess form 10 hours to 10 seconds.
* One of the glitch ''[=~Pokémon~=]'' is [[http://bulbapedia.bulbagarden.net/wiki/Charizard_%27M Charizard 'M]]. From the entry at Bulbapedia: "Charizard 'M can also change all of a player's party Pokémon into Charizard 'M, but the moves and type do not change, and putting these "transformed" Pokémon into a box makes the other Pokémon Charizard 'M also."
** For that matter, the ''Pokémon'' series has an actual gameplay mechanic called the "Pokérus", which your Pokémon can pick up randomly during the game. This isn't a ''bad'' thing by any means though, and actually helps your Pokémon get stronger stat boosts when they level up. It also wears off after a few days.
*** They stop spreading it after a few days, that is. Any pokémon that's ever had the virus will retain the speedy growth forever. It also "freezes" when the pokemon's in a box, allowing you to keep a few virus-spreaders handy for when you need to infect more of your mons.
* ''StarFox Assault'' has the Aparoids, a robotic insect colony from another dimension that infects both biological creatures and mechanical objects.
* Alma does this to Sergeant Keegan in ''[[{{FirstEncounterAssaultRecon}} F.E.A.R.: Project Origin]]'', using her psychic powers to literally make him fall in love with her. The only way to save him is to kill him.
** Not quite. [[ItsAllThereInTheManual His datafile]] shows that he was already highly synchronised with Alma, naturally, and she as got more... ''enthusiatic'', she accidentally {{MindRape}}d him. She was only ever interested in [[spoiler: you]].
* For a technological example: the unnamed computer super-virus from ''{{Descent}}'', which takes over mining robots and [[TurnedAgainstTheirMasters turns them against humans]], while at the same time drastically increasing their AI. It's much more powerful in the novel adaptations, in which the virus can take over just about any machine and give it sentience, and possesses AI of its own, allowing it to intelligently react to and avoid anti-virus measures.
* The StrangeVirus from {{Puzzlebox}} boosts a person's resilence to injury, inspires creativerty and sends its hosts mad.
[[/folder]]

[[folder:Web Comics]]
* The revenants in ''GirlGenius''.
* The Dimension of Pain demons from ''SluggyFreelance'' possess a spear that can turn human beings (and ferrets, apparently) into demons, and they use it frequently during their [[DemonicInvaders invasion]] of the Dimension of Lame. However, since the spear can't completely get rid of the humans' inherent wussiness, the result is an army of pretty wussy demons.
* The Legion from ''MSFHigh'' are a legion of {{Green Skinned Space Babe}}s who, when forced to fight, turn their attackers ([[OneGenderRace whether male or female]] to begin with) into Green Skinned Space Babes who see things their way. That's in the present; they worked similarly in the past, but replace "attackers" with "defenders" and "see things their way" with "lose all of their original personalities and fight mindlessly for the Queen."
[[/folder]]

[[folder:Web Original]]
* The ''SCPFoundation'' have a dossier on [[http://scp-wiki.wikidot.com/scp-217 SCP-217]], which is basically The Virus plus [[CyberneticsEatYourSoul Clockwork Eats Your Soul]].
* ''WhateleyUniverse'' examples: The Palm is a [[AIIsACrapshoot living artificial intelligence in the internet, trying to replicate and wipe out all human life. In a much creepier variant, in the story "The Op", this is what the heroes face, complete with BodyHorror and WombLevel.
* This wiki. ThisTroper has personally infected two others into becoming tropers.
** This troper was infected by a family member! {{Squick}}.
[[/folder]]

[[folder:Western Animation]]
* Baron Dark from the cartoon ''SkeletonWarriors'' could change anyone not "pure of heart" into a titular Skeleton Warrior.
* The Skeleton King from ''SuperRobotMonkeyTeamHyperforceGo'' does not have that restriction for making zombies.
* Beautiful joke example from ''TheTick'': when reminiscing about past adventures, Captain Decency remembers the time a villain built a superweapon known as the "Ray Gun". This gun functioned by turning anyone it shot into a duplicate of "some guy named Ray", depicted as a gas station attendant with the nickname "Ray" on his coveralls. Cue incredibly creepy TwilightZone-style black-and-white shot of a town filled with identical Rays saying "Hi, I'm Ray!" to each other over and over. Captain Decency then begins to reminisce about a similar adventure involving a "Tommy Gun" before being cut off.
* In ''{{The Pirates of Dark Water}}'', the titular Dark Water had the ability to kill people outright, or [[TheCorruption corrupt them]] into mutated minions or mindless slaves. In one of the more NightmareFuel-laden episodes, an elderly woman tries ingesting a drop of it in a youth potion and it winds up ''consuming her completely from the inside.''
* Daemon was a literal software virus in ''{{ReBoot}}''. As were Megabyte and Hexadecimal, but only the two formers showed the ability to infect sprites.
* In ''CodeLyoko'', some of XANA's attacks follows this route, the specter first possessing one animal then spreading the control to others (rats in "Plagued", wasps in "Swarming Attack"). In "Attack of the Zombies", a possessed Kiwi can transmit The Virus to humans, ZombieApocalypse–style.
* A robot from a planet of robots fears humans are The Virus in the ''{{Futurama}}'' episode, "Fear of a Bot Planet".
-->'''Robot:''' Is it true, humans sneak into your room at night, drain your fluids, and ''turn you into a human''?
* Played for laughs in an episode of ''Camp Lazlo''. It's learned in this episode that when Samson gets sick, his germs can cause others to at first, get sick, and then end up looking a lot like a hamster who is sick,
* The Xenocites from ''Ben10AlienForce'', when placed on a carbon-based lifeform, transform them into a [=DNAlien=] under the thrall of the [[ScaryDogmaticAliens Highbreed]]. [[spoiler:Thankfully, the Omnitrix has the power to revert the genetic damage and restore the original form of the victims.]]
* The original ''{{Transformers}}'' has the HatePlague from Outer Space which was unleashed upon the Earth. At first it appears to make those infected fight others and themselves, but later on it just appears to make them act like jerks with the intent of infecting others. Either way, the last known hope to the world, nay, universe is to revive Optimus Prime. It works, of course, and even Galvatron is thankful enough to call for a truce. For now.
** Much later, in ''BeastMachines'', technomatter made with the Key to Vector Sigma had much the same effect - when the Maximals were zapped with the Key, they became both contagious and mentally unstable, and tried to infect each other.
[[/folder]]

[[folder:Real Life]]
* In a televised debate between JackThompson and Adam Sessler (of ''{{X-Play}}''), the effects of violent video games were likened (in so many words) to a virus corrupting everything it touched. The twist: it was actually Adam bringing up the metaphor, [[TheWarOnStraw hijacking Jack's argument]] and [[ChewbaccaDefense trying to make it sound ridiculous]]... to which end he filibustered about it for the remainder of the allotted time without letting Jack get a word in edgewise.
* Strange Matter, which changes everything it touches into more Strange Matter.
* And, of course, viruses. They tend to do it on a microscopic scale; a popular method is for a virus to inject its genetic material into a cell, which corrupts it, making it produce more viruses inside iteslf. It then bursts, spreading many more viruses throughout the body and killing the cell in the process.
[[/folder]]

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