The Virus - Television Tropes & Idioms

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, Megaframe: my domain. My format, Virus: To corrupt and conquer!
— Megabyte, Reboot

loneliness + alienation + fear + despair + self-worth ÷ mockery ÷ condemnation ÷ misunderstanding x guilt x shame x failure x judgment n=y where y=hope and n=folly, love=lies, life=death, self=dark side
— The Anti-Life Equation

The Virus comes in many forms in many genres. Simply put, the virus turns people into itself or into entities subservient to itself. The transformation is both mental and 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 get them back. Despite the body snatching, if The Virus is only able to crudely mimic human behavior it may lead to a Glamour Failure. If the Virus mutates their host to the point where they are almost unrecognizeable, expect it to do the same with environments. This tends to lead to the Womb Level and Organic Technology.

How much of the former person is left after infection depends on the series, as does whether or not the process is reversible. It also depends on whether it's a main character or not, they can sometimes use The Virus' powers against it with enough Heroic Willpower (a property more typical of The Corruption). If The Virus is sentient, then more often than not it is also a Hive Mind with a Hive Queen directing it.

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

Often how humans become something much, much more horrible.

Sometimes overlaps with Body Horror in cases where the host enters a zombie-like state before being completely consumed. Compare Viral Transformation, where a similar change does not cause a Face Heel Turn. See also The Puppet Masters, Face Full Of Alien Wing Wong.

Examples

Anime and Manga

The Invaders from the anime Gatekeepers and its dark sequel, Gatekeepers 21.
Venus Versus Virus: The Virus is actually called that; it changes humans into demons.
Mermaid Melody Pichi Pichi Pitch has Yuuri's hypnotic piano playing.
Many of the Hollows in Bleach are Pluses (ordinary ghosts) that were caught by other Hollows.
The Festum in Fafner In The Azure Dead Aggressor
In one chapter of The Kurosagi Corpse Delivery Service, a real-life virus that infects snails begins to infect humans instead, with art that puts the horror back in Body Horror.
This happens to entire planets in the Salamander OVA.
Higurashi No Naku Koro Ni takes this in a somewhat weirdly literal direction with Hinamizawa Syndrome. Once someone's case has been aggravated, you really can't bring them back easily. Although there are exceptions.
The Dark Spore in Digimon Adventure 02, though it's effects tend to be somewhat More Than Mind Control.
Blue Drop has a somewhat lesser example. The second manga, Tenshi no Bokura, implies that any human female sexually exposed to the One Gender Race 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 horrific.
DG Cells from G Gundam, proving that the only thing worse than zombies are cyborg zombies. With giant robots.
The anime of the series Le Chevalier D Eon 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 Red Garden 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 super human. One of them also walks like a dog.

Comic Books

The OMAC from The DCU 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 Marvel Universe 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, (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 Legion Of Super Heroes features the Blight, which ravages the United Planets and takes over most of the Legion before the remaining Legionnaires manage to purge it.
In DCU's Final Crisis Big Bad Darkseid uses the Anti-Life Equation this way, bringing Earth under his control, and transforming some of the heroes into his monsterous servents.

Films

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 begins sprouting tentacles, giant toothy mouths, etc.
Agent Smith in the Matrix sequels.
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 Hive Queen, controlled through a Hive Mind.
Cabin Fever is a possible subversion of this. The disease ITSELF isn't actually as bad as it looks, it's just a skin disease. It's everyone's reaction to it that the horror comes from.

Literature

The 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 sex.
A unique example from Charles Stross' 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 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 Deal With The Devil. 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 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 Hive Mind culture in Alastair Reynolds'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 goes bad when the increased self-preservation instinct causes him to search out more and more hosts.
Faction Paradox in the Doctor Who 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 the Doctor.

Live Action TV

The vampires from Buffy The Vampire Slayer. Buffy vampires have their previous selves' souls replaced with a demon (save for a couple of notable exceptions). However, 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 controled by the 'mother' demon below the school.
The Borg from Star Trek.
The Cybermen of Doctor Who, who were arguably the inspiration for the Borg.
- The "Empty Child" in the new Doctor Who series (from the episodes "The Empty Child" and "The Doctor Dances") was 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.
- The Bane fizzy drink from The Sarah Jane Adventures 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 Azazel infected Sam with his own blood the night of the fire more than likely covers it.
Inverted in Stargate Atlantis, where the "good guys" invent a virus that turns enemy Wraith into docile, submissive humans. Of course, they really don't go about this in the best way, and things quickly go downhill.
The Orphenochs from Kamen Rider Faiz.
A key trait of Dezumzorya, the Big Bad of Bakuryu Sentai Abaranger. It combines physical infection with More Than Mind Control 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.

Opera

The opera Help, Help, The Globolinks! has 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.

Tabletop Games

Dungeons And 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 Cosmic Horror, also gives this power to Sealed Evil In A Can Father Lymic, with the Brood created by him given a fraction of his Elemental Powers over ice. His goal is to ultimately corrupt the world, turning it into a Single Biome Planet of snow and darkness. Yeah, he's scary.
GURPS had, 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 Chaos, which can quite effectively turn the open mind into a willing cultist and a traitor to mankind.
- You also have the insidious Tyranid swarms, the insidious Genestealer cults, the insidious Tau propagandists/brainwashers, the insidious Necron Pariah harvest, etc., etc., etc. Rarely is any given conflict zone in 40K NOT subject some form of The Virus. Let's just say that in this universe, General Ripper typically has the right idea.
- And of course, there's the dreaded Obliterator virus, which turns you into 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.
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. 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 psionic in nature), with... interesting consequences if that computer happened to control (for instance) a nuclear reactor or a life-support system. Then it evolved full intelligence, which didn't improve matters.
One of Feng Shui'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 Zombie Apocalypse 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".

Video Games

In the video game Prototype, the character 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 (and ONLY warehouses for some obscure reason) to produce beefed up mutants that are incredibly annoying.
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 almost every video game franchise produced by Blizzard:
- Diablo 2. The protagonist from the first Diablo game is, after jamming the soulstone of Diablo into his head, transformed first mentally, then physically, into a servant of Diablo and ultimately into Diablo himself. The same fate befell the archmage Tal Rasha, transforming him into Baal after he had Baal's soulstone lodged in his body.
- Starcraft has the Zerg, who first "infest" their prey with mind-controlling insect larvae and then bodily transform them into chitonous, telepathic servants of the Hive Mind Swarm. The race, however, is primarily concerned with operating as some kind of genetic Planet Looters, seeking to assimilate favorable DNA (rather than the organisms themselves) from all species they encounter, before exterminating said species wholesale.
- War Craft. 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.
- And when the Flood hijack enough bodies, they build a Gravemind; a giant, rhyming, Magnificent Bastard Hive Mind.
Though it involves no physical changes aside from a possible pallete swap, the Maverick Virus from the Mega Man X franchise otherwise qualifies.
- And after the Maverick Virus in Mega Man ZX Model W gained the ability to manipulate the thoughts of humans and Reploids alike. This became important for Albert's Xanatos Gambit .
Final Fantasy VII 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 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 Non Standard Game Over.
Metroid Prime'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 dead.
  - The X Parasites from Metroid Fusion are a more traditional version of this trope, as their only purpose is to infect more people.
Mass Effect includes the Thorian, which is a plant-like entity that uses spores to mentally control people through pain. Also, there's 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 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 Enemy To All Living Things (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 Superpowered Evil Side.
- The Corrupted, from the sequal, are an aversion-it's pretty much their own damnn fault they're Eldritch Abominations 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 Multiple Endings, 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.
Resident Evil is replete with these, both in the form of literal viruses, and the Las Plagas parasites.
Knights Of The Old Republic has rakghouls, deformed mutants with infectious bites, living in the Undercity of Taris. The player character cannot be infected, but several infected NP Cs 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 The Remnant.
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 Nonstandard Game Over 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 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 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 That One Boss.
The old Area51 lightgun game revolves around an alien virus being unleashed and causing a Zombie Apocalypse in the area. The Game Over screen shows a video of the protagonist morphing into one of the alien mutants.
Dead Space '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.
One of the glitch Pokemon is 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 Pokemon series has an actual gameplay mechanic called the "Pokérus", which your pokemon can pick up randomly during the game. This isn't a bad thing by any means though, and actually helps your pokemon get stronger stat boosts when they level up. It also wears off after a few days.
Star Fox 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 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. His datafile shows that he was already highly synchronised with Alma, naturally, and she as got more... enthusiatic, she accidentally MindRaped him. She was only ever interested in you.
For a technological example: the unnamed computer super-virus from Descent, which takes over mining robots and 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.

Web Comics

The revenants in Girl Genius.
The Dimension of Pain demons from Sluggy Freelance possess a spear that can turn human beings (and ferrets, apparently) into demons, and they use it frequently during their 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.

Web Original

The SCP Foundation have a dossier on SCP-217, which is basically The Virus plus Clockwork Eats Your Soul.
This wiki. This Troper has personally infected two others into becoming tropers.

Western Animation

Baron Dark from the cartoon Skeleton Warriors could change anyone not "pure of heart" into a titular Skeleton Warrior.
The Skeleton King from Super Robot Monkey Team Hyperforce Go does not have that restriction for making zombies.
Beautiful joke example from The Tick: 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 Twilight Zone-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 corrupt them into mutated minions or mindless slaves. In one of the more Nightmare Fuel 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 Re Boot. As were Megabyte and Hexadecimal, but only the two formers showed the ability to infect sprites.
In Code Lyoko, some of XANA's attacks follow 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, Zombie Apocalypse–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 Ben 10 Alien Force, when placed on a carbon-based lifeform, transform them into a DNAlien under the thrall of the Highbreed. Thankfully, the Omnitrix has the power to revert the genetic damage and restore the original form of the victims.
The original Transformers had the Hate Plague from Outer Space which was unleashed upon the earth. At first it appeared 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.

Real Life

The Virus is probably emblematic of viruses in general: they replace the DNA of healthy cells with their own and reprogram it to make more viruses.
- Rabies is the best example. It does not exactly control its host mind, but it does often induce aggression and increased saliva production. Both of this symptoms help the virus to spread.
- Toxoplasmosis which is commonly found in cat feces, but can infect multiple species. When mice are infected, they behave strangely, and take unnecessary risks, making them more likely to become cat food, and thus pass on the infection. In fact, this certainly isn't the only parasite to spread by causing its host to sacrifice itself. Toxoplasmosis is caused by a protozoan, not a virus. It is speculated to have similar effects on humans in increasing risk-taking behavior. Aside from cat feces, it can also be contracted as a food-borne illness in undercooked meat. It is estimated that between 30 and 60% of the human population on average carries the parasite, inflating to as much as 88% in France. Yikes.
- Although not caused by a virus (it's caused by a protozoan instead), African trypanosomiasis (sleeping sickness) kind of fits here too, since the parasite reprograms the victim's brain to make them sleep all the time.
- Another parasite, Leucochloridium paradoxum infects snails and, as well as making their antennae swell and pulse with color visibly, takes over their brains and causes them to move to a high, easily visible point where they will easily be spotted and eaten by birds (to be passed on in their faeces).
- Several species of horsehair worm infect insects. When they reach their adult stage, they "enslave" their host and send him to the nearest water, so that the adult worm can burst out of its victim (shades of Alien) and swim away.
- Similar to the above example, Gordian worms, aka Nematomorpha, compel their hosts to leap into water and drown themselves, so they can escape and continue their life cycle. There's also some graphic video of one turning it's host, a praying mantis, inside out as it emerges.
- Tapeworms, which infect many species, including humans, are mostly harmless as adults but their larvae are another story. They actually feed off your immune system and some like Echinococcus can swell into cysts the size of a soccer ball while inside you.
- The bacterium Wolbachia infects the reproductive system of it's insect hosts. Since they can only be passed on from mother-to-daughter, the bacteria kills male embryos, transforms them into females, and makes their female hosts into sluts. They can even make an infertile fruit fly fertile. Wolbachia has become symbiotic with its host filarial worms, which are themselves responsible for some sickening diseases: elephantiasis, loa loa, river blindness, etc. Bizarrely enough, if antibiotics are used to kill the Wolbachia, the worm will either die or become sterile.
The Cordyceps fungus is a fungus which targets insects as hosts. According to the wildlife documentary Planet Earth, one particular strain actually makes the ants it infects climb up to the highest point it can get before dying so the fungus' spores can spread as far as possible.
In a televised debate between Jack Thompson 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, hijacking Jack's argument and 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.