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Grey Goo

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"'Plants' with 'leaves' no more efficient than today's solar cells could out-compete real plants, crowding the biosphere with an inedible foliage. Tough, omnivorous 'bacteria' could out-compete real bacteria: they could spread like blowing pollen, replicate swiftly, and reduce the biosphere to dust in a matter of days. [...] Among the cognoscenti of nanotechnology, this threat has become known as the 'gray goo problem.'"
K. Eric Drexler, coining the term

Grey Goo is like a Horde of Alien Locusts, only replace Alien Locusts with Nanomachines or any other self-replicating material — and instead of grass, they "eat" anything. Or, if the protagonists are lucky, just anything mineral, metal, or electronic.

They're worse than alien locusts. Grey Goo destroys resources by turning them into more grey goo — more nanomachines or whatever matter the grey goo is composed of. It's The Virus for nonliving things — though it may be able to take down living things as well, and likely will turn them into nonliving things if they're in the wrong place (i.e.: outside). In theory, you can end up with a planetary body made of nothing but grey goo. Physical laws regarding energy, thermodynamics and the like are an obstacle, but even a partial success in this case is likely to suck for everyone involved.

If you want to guarantee large scale destruction with free Green Aesop implications, make your goo specifically designed to clean up oil spills so that it has a built in taste for organic compounds, and is hard to kill.

Essentially always a Snowballing Threat as an antagonist. Can cause The End of the World as We Know It — typically anything up to a Class X on the Apocalypse How scale — and is very often considered a Superweapon as a result.

Compare Blob Monster, Planet Eater, Explosive Breeder and Clone by Conversion. For the Real-Time Strategy game about (and playing as!) the grey goo, see Grey Goo (2015).


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    Anime & Manga 
  • Grey goo has completely devoured Mercury by the time of Battle Angel Alita.
  • The title creatures in Bio-Meat: Nectar.
  • Black★★Rock Shooter: Dawn Fall has Arche, grey goo composed of sperm-like nanites that can break down both organic and inorganic matter. It's so prevalent that humans have to wear masks to avoid breathing the stuff in. Unusually, Arche can not only self-replicate, but also construct new machines for Artemis, the AI it serves. The Ishtmus of Panama has been turned into a giant lake of the stuff, dubbed the "Iron Ocean", into which humans are fed and from which new machines are constructed. Black★Rock Shooter can also manipulate the stuff to construct her signature BFGs.
  • The D-Reaper from Digimon Tamers is a very slow form of Grey Goo, breaking down inorganic matter and reconfigure it into its various agents once it emerges in the real world. It's depicted as a mass of red goo in the series because its actually super-heated to extreme temperatures by accelerating its particles beyond the speed of light.
  • The culture fluid from Dragon Ball Z: Bio-Broly multiplies when it absorbs a person, the stronger, the better. After absorbing Bio-Broly it expands to cover the whole island but luckily seawater turns it to stone.
  • Gundam
    • ∀ Gundam features Black Goo in the form of the Moonlight Butterfly (Gekkōchō), which is named because it manifests as giant shimmering energy contrails that emerge from the titular Humongous Mecha's back like wings. The nanomachines only target technology, but do so on an immense scale; the last time the Moonlight Butterfly was used, it sent humanity into a Dark Age that they're still recovering from (when the series begins, technology is roughly on par with the early 1900s).
    • In Yoshiyuki Tomino's original novel, the full powered version of the eponymous Gundam can affect the area from Earth to Jupiter with the Moonlight Butterfly — that's over 600 million miles.
    • The DG Cells in Mobile Fighter G Gundam are a combination of this and The Virus, though strangely enough they were designed to be beneficial, as their original purpose was breaking down dead or decaying matter and using it to foster new life. The Devil Gundam instead uses them to reanimate dead humans under its control, or infect live humans and Mind Control them.
    • The G-Lucifer in Gundam: Reconguista in G (a series that takes place after Turn A Gundam) also has a Moonlight Butterfly system.
  • The WORMS in Sky Girls are related to this. Sort of.

    Comic Books 
  • In Atomic Robo, Biomega (the setting's resident Kaiju) turn out to be a biological form of this. If left unchecked, they will eventually devour the Earth, then the solar system, the galaxy, other galaxies...
  • What happened to Negaduck after being hit by the Tron-Splitter at the end of the Darkwing Duck story "Crisis On Infinite Darkwings".
  • Adam Warren's adaptation of the Dirty Pair revealed that the Earth had been destroyed decades earlier in a massive Grey Goo outbreak, the "Nanoclysm", which led to nanotechnology being regulated and virtually outlawed. The villain of the miniseries planned to use a cache of nanotech to take over Heroes "R" Us's Central Computer, and from there, the known universe. Unfortunately, the Central Computer revealed that it was partially based on something the Nanoclysm left humanity as an apology…
  • Empowered has a Grey Goo eruption that created Sexbots, for reasons too complicated and silly to explain but which involved someone trying to use alien nanobots with an untranslated interface for perverse purposes.
  • One issue of Fantastic Four claimed that the reason Reed has never tried to market the unstable molecules the team's suits are made out of is that if a careless person gets ahold of the stuff and pokes it the wrong way with an electron microscope, it starts destabilizing all surrounding matter into an ever-expanding blob of goo. Naturally in that issue someone careless got ahold of the stuff.
  • The Filth features creatures like this, but portrays them in a very sympathetic light during the stages of their evolution. The more they spread, the more the world is seen from their perspective.
  • Iron Man's Technovore is a nanotechnological entity driven to assimilate and integrate foreign technology into itself.
  • One of the early comic issues of MAD had the planet Mars consumed by the Gookum, a jelly-like pink substance which eats anything organic. It breaches The Great Wall built to contain it, and, worse, It Can Think. It stays dormant for 500 years at a time, and the joke/Mandatory Pulp Sci-Fi Twist is that cherry Jello parfait is completely indistinguishable from dormant Gookum. One day... one day the Gookum will quiver, will stir...
  • The eponymously-titled "Grey Goo" story in Issue #21 of Regular Show sees Rigby accidentally releasing nanites that attempt to consume everything around them. They also have artificial intelligence.
  • Sonic the Hedgehog (IDW): The Metal Virus. It is literally grey goo (it looks like liquid metal) that spreads between all organic being, and converts them to "zombots", starting a mechanical Zombie Apocalypse. Just a single touch is enough to infect anyone and anything. A fly can get infected by touching an infected person and then the fly will touch somebody else and infect them and the person running over the grass will turn the grass to metal that will infect the trees, and it just. keeps. going. Silver travels back to time reporting that in the Bad Future there is absolutely nothing left on earth but ruined cities and and bits of metalic plants. The Metal Virus damn near brings the planet to its knees in a matter of days. If Sonic was one second slower, life would just be gone.
  • The Modular Man from Tom Strong is a hi-scale example of this. Each individual module is about the size of your head. Once he gets to Venus, though, he multiplies until he has something closer to the proper Grey Goo appearance.
  • Transmetropolitan:
    • This is mentioned as a possible weapon if the commonly used "makers" are reprogrammed. The standard MO for handling a "grey goo" scenario is to release "blue goo" — disassembler nanites that degrade matter, all matter, to the point that grey goo can't make more nanites out of it, and then destroy the grey goo nanites — to contain the grey goo and restrict its damage to a small area. One brief mention is made of someone who lost his legs because he decided to shut off the grey goo instead of releasing the blue goo (and succeeded). He's then fired for violating protocol and ends up homeless.
    • Foglets — people who have their minds uploaded into a swarm of nanocomputers — work on a smaller scale, since the most practical way to turn someone into a Foglet is to have another Foglet do it. (They can reassemble matter on a molecular scale, so building the drones is easy.) Since they're controlled by a human intelligence, they don't go out of control and start destroying everything. At least, they haven't so far...

    Fan Works 
  • Hermione Granger The Arithmancer realises that it's possible for a combination of transfiguration and runic magic to create a self-replicating swarm, and promptly freaks out until she examines the problem more carefully and decides that it would be very hard to accidentally create a self-sustaining swarm; most configurations would eventually degrade and/or run out of power. She does create a carefully limited swarm for herself as a last-ditch weapon, and uses it to kill Bellatrix Lestrange.
  • This is the final fate of Earth in Friendship is Optimal.
  • In Project Sunflower, a meteor crashed into earth carrying a colony of alien nanomachines that consumes everything on the planet, forcing humanity to jumpstart the eponymous interdimensional portal project to find a new home.
  • The Secret Return of Alex Mack: The Collective loses containment on a self-replicating nanobot swarm in Nevada, prompting a Heroic Sacrifice by Shar to wipe it out in spectacular (yet traumatic) fashion.

    Film — Live-Action 
  • The Blob (1958): The monster could be either this or The Virus. No one's really ever gotten close enough to examine it without being eaten. All that's known about it is that it's of alien origin. Oh, and it prefers to devour organic life as opposed to inorganic matter.
  • The Blob (1988): The remake of the movie had the Blob be the spawn of a secret government germ warfare project. There it acted less like mindless spreading Grey Goo and more like a malicious, semi-intelligent monster.
  • "The Lonesome Death Of Jordy Verrill" from Creepshow features the opening phase of a Green Goo scenario, as Jordy and his farm are overgrown by the alien "weeds".
  • The Day the Earth Stood Still (2008) tries to reboot the Earth with this. It was more a "Grey Cloud" than Goo, but same strategy.
  • G.I. Joe: The Rise of Cobra had "Red/Black" weaponized Goo (which is green for the viewer's convenience), which ate any metal it came into contact with. Thankfully, the designers were smart enough to build them with cutoff switches which neutralized them instantly. It also had a limited life span which meant that if its food source was too far away it would die out, depending on how much of a start it got. Eating the Eiffel Tower would give it enough of a start to devour all of Paris, but it would likely not reach another city. Devour a single ship high in the stratosphere and it dies out long before it reaches anything else. It's unlikely that the nanomites were self-replicating at all. A self-replicating nanomachine is, by necessity, much more complex that a simple molecular disassembler. And if you're foresighted enough to build in a kill-switch, the very last thing you'd want to risk is the possibility of generational copying errors disabling that function.
  • Ego's plan in Guardians of the Galaxy Vol. 2 involves this, albeit in an organic fashion: he plans to make every planet in the universe an extension of him by way of implanting a piece of him on each planet that, when activated, creates a giant blue blob that eats everything in its path. Although we don't see much of what it does besides "consume things", we can assume that it assimilates everything it touches into Ego.
  • In Superman Returns, Lex Luthor creates a Kryptonian island that will grow over America if not stopped. The novelization and Comic-Book Adaptation imply that it's growing into a planet after Superman pushes it into space.
  • In The Thing (1982) and its 2011 prequel, the so-called "Thing" is an organic variant that gruesomely assimilates living tissue.

  • An über-example would be Charles Stross' Accelerando, where pretty much the same events as in Bloom happen deliberately, and for the betterment of mankind.
  • Aeon 14: Nanotechnology is common in the series and nanotech weapons easily combated. However the picotechnology mastered by scientists aboard the colony ship Intrepid is potentially very dangerous: the Intrepid Space Force under Tanis Richards successfully uses picobombs several times against opposing ships, but there are reports of people trying to replicate the weapons and getting entire planetary civilizations eaten for their troubles (or killed by Orbital Bombardment when the Orion Guard gets wind of the experiments, in the case of the birth family of Tanis's adopted daughter Sanavi).
  • In Walter Jon Williams's Aristoi, a form of grey goo (called "mataglap nano") destroyed Earth That Was. As a result, only the eponymous Aristoi are legally allowed to use nanotech freely and they are fanatically paranoid about the possibility that any given form of nanotech could somehow mutate into mataglap.
  • In Greg Bear's Blood Music, the Green Goo is not nanotechnology, but biotechnology, but operates in basically the same fashion. The "noocytes" consume all the biomass in North America, converting it to more noocytes. It turns out that all the living creatures who are assimilated are also recorded and "alive" in a new kind of reality, similar to "Bloom" below.
  • One of the best examples is Wil McCarthy's Bloom, a novel set in a future where the last fragments of humanity lives in habitats in the asteroid belt and in jovian orbit, after the entire inner solar system was devoured in a Grey Goo incident. Earth, Venus, and Mars are now large fuzzy balls of nanotech, nanotech solar sails drift aimlessly throughout the system, and occasionally errant strands drift out on the solar winds and try to devour anything they touch in the outer solar system. It's okay, though, because the billions of people devoured in the incident are merely compressed, not gone, and their brain engrams still survive in the bloom, immortal and living in virtual paradises of their own construction; imagine how powerful a computer would be if it was made from an entire solar system?
  • Hal Duncan's The Book of All Hours has Magitek nanites charged with the souls of dead gods. It's an ideal medium for carving new identities on people's minds and souls by tattooing their bodies. A large collection also gets loose at the end of the first book, leading to a Grey Goo scenario that gnaws at the very substance of reality. All that's left are pockets of semi-stable time and narrative as spacetime gets even more fractured than it already was.
  • Ice-nine in Cat's Cradle turns any water it touches into more ice-nine.
  • Century Rain by Alastair Reynolds has Earth effectively uninhabitable from the effects of rogue swarms of nanobots. The nanobots were originally created to affect weather patterns, but they were corrupted. New bots were created to fight those, which went rogue, and so on and so forth. The survivors from the disaster, who now reside in orbital habitats, weaponized the Grey Goo and use it as a weapon of mass destruction.
  • In Jack McDevitt's Chindi, an ancient alien satellite that has already mysteriously destroyed one ship is being much more carefully investigated by a second when the ship begins to come apart. It turns out that the satellite uses grey goo to repair/replicate itself, and the ship is being eaten. Several people die, and one, the artist with a big crush on Hutch, is rescued just in the nick of time.
  • The title Extreme Omnivore Blob Monster in the The Clone has some shades of this, although it's green and not grey. Nearly everything it touches, organic and inorganic, it converts directly into more of its own body mass.
  • In John C. Wright's Count to the Eschaton, the Savants used Golden Goo. It destroyed the cities, where it was released first — killing most people there, with only a few stunned to be transferred with their minds intact — and only by savage, fiery attack by the Giants was the earth saved from their "Golden Age."
  • Death from the Skies by Phil Plait presents a berserker Von Neumann probe, which is essentially grey goo on a cosmic scale.
  • In Deltora Quest, the Shadow Lord has a literal grey goo flood set up as a final Xanatos Gambit. It was designed to kill everything on the continent, but the Shadow Lord didn't count on dragons.
  • Played with in The Dervish House by Ian McDonald. The Grey Goo scenario is a common fear in the near-future setting due to a famous scientist's doomsday predictions of a nanotech catastrophe, even though it's generally accepted that he was just fearmongering and was wrong. A character later comments that the Grey Goo scenario has already happened; it's called organic life. It turns out that self-replicating nanotechnology is key to a massive terrorist attack, but not in the traditional sense.
  • In The Forge of God by Greg Bear, this is done deliberately and systematically by a belligerent alien race, to humanity as well as at least one other race. The sequel, Anvil of Stars, is the story of a handful of the survivors of Earth — specifically, the children — seeking out the race that destroyed Earth, to enact the Law.
  • The Four Horsemen Universe: The Bounty Hunter protagonist of the Short Story "The Last Guardsman" is mortally wounded when his quarry wings him with a grey goo bullet that eats him alive from the inside out.
  • The novel How to Mutate and Take Over the World ends with nanites from a dessert factory transforming the world into key lime pie. And this gets spoiled about a third of the way in, in a fictional review of the book.
  • John Carter of Mars: In Synthetic Men of Mars something goes horribly wrong in one of the tissue vats from which the Hormads are created; instead of individual Hormads, one colossal pile of flesh, bone, organs etc. is created, with multiple arms, screaming heads and other body parts sticking out. It keeps growing, sustaining itself by eating its own fleshnote , and threatens to eventually engulf all of Barsoom.
  • Charles Pellegrino and George Zebrowski's The Killing Star includes weaponized Grey Goo which is used to pick off one of the few surviving outposts of humanity.
  • In The Long Cosmos, one of the parallel Earths has been entirely devastated by a matter replicator run amok. The matter replicator was originally supposed to absorb enough vegetable matter to produce a book of the complete works of Shakespeare, but once a glitch caused it to produce another replicator just like it... which in turn produced other replicators. It did not help that the replicator owner, who was only concerned with spreading the knowledge of Shakespeare across the parallel Earths, completely failed to anticipate the dangers of a rogue self-replicating machine let loose on a planet.
  • In the short story "Mar Pacifico" by Greg Mellor, nanotech designed to fight the effects of global warming (by letting the oceans absorb more carbon) sweeps over the Earth absorbing most forms of life. When the protagonist is absorbed, she discovers that humanity still exists as a linked Hive Mind inside the nanotech.
  • In Prey by Michael Crichton, the main plot is a Grey Goo experiment which has gone rogue and escaped containment. This one's slightly more innocuous in that it's partly biological and relies on E. coli bacteria to produce new nanobots rather than instantly dissolving anything it touches into more goo (it does seem to have some limited ability to "eat" silicon chips from integrated circuits). Of course, this really just means it needs to find a culture medium to grow E. coli in, and there are all these bags of moisture and nutrients wandering around...
  • In the Revelation Space universe the humans finally wipe out the all-destroying robot race that's been killing all the spacefaring races - only to discover they were keeping in check a much worse all-destroying robot race: out-of-control terraformers called Greenfly. They were programmed to convert matter and energy into vegetable-rich biospheres, and they're doing it with enthusiasm - with all the matter and energy. They end up driving the remnants of humanity out of the Milky Way altogether, and may or may not eventually go on to consume the entire universe.
  • Neatly inverted in Charles Stross' Saturn's Children—robots think of organic life as "pink goo," reproducing without limit.
  • Discussed derisively in Schild's Ladder, which is set in a post-Singularity galactic society: an AI character mentions the conspiracy theory that metaverse-dwelling minds would assimilate planets for computational resources, calling it as preposterous as accusing organic beings of plotting to turn the world into chocolate for infinite desserts.
  • In Spy Gear Adventures, this is the focus of the fourth book, The Doomsday Dust, and Cyril explains the trope by name to the others.
  • In SA Swann's Terran Confederacy universe, the human colonies on Titan and the outer moons were devoured by a Grey Goo swarm, leading to Nanomachines being made one of the Heretical Technologies. The Confederacy and its successor states continued this policy, enforcing it with things like hundred kilometer asteroids. It's the Only Way to Be Sure!
  • In one of the Thursday Next novels, Thursday's time-traveling father tells her of a future wherein the world was overtaken by such a scenario; the world is consumed by pink slime. It turns out to be strawberry pudding.
  • In Scott Westerfeld's book Specials, the main characters break out of a weapons storage facility using nanotechnology-based silver goo (much more flashy and dramatic than plain old gray goo, to paraphrase the author).
  • A rather spooky example presented here as a story, which shows us why you should just let the gray goo be...
    • And played with in this story on the same site, where the sentient gray goo triggers the nanoapocalypse to save humanity from an impending asteroid collision.

    Live-Action TV 
  • A failed pilot for a TV series called Doorways by George R. R. Martin featured a parallel dimension where, yep, nanomachines used to eat up oil spillages went and ate all the oil. This scenario was the result of Executive Meddling — G.R.R.M's original script (and the one found in his "Dreamsongs" retrospective compilation) featured the parallel Earth as a Winter World, but this was apparently too bleak for a first episode.
  • The villain Mantrid in the second season of Lexx used Mantrid drones — basically flying arms — to systematically disassemble and convert all matter in the universe into more Mantrid drones. By the end of the season, nearly three-quarters of the universe had been converted, and the remainder would have been finished off within a few days. Kai tricks Mantrid into flying the sum-total of his drones directly to the center of the universe, precipitating a Big Crunch which destroyed that universe but ejected the Lexx and crew into the next one over.
  • PixelFace: In "You're History", Alexia receives a gift from her Russian uncle: a red jigsaw block. But the block starts multiplying, and soon the console is overrun with coloured shapes falling out of the air. And these shapes are replicating by 'eating' the console's memory. If they consume all of it, everything in the console, including the player characters, will be wiped out.
  • The Replicators of Stargate SG-1 are this trope scaled up to Lego size. When they eventually evolved to silver goo, their diet changed from "any kind of metal" to "neutronium only", thus keeping the new model a rarity.
  • A minor example of this is the nanite colony Wesley Crusher is running in the Star Trek: The Next Generation episode "Evolution". Fortunately, this goo turns sentient and is willing to be moved to a better food source before it disables the ship.
  • In the Stitchers episode "Two Deaths of Jamie B", the eponymous victim was trying to make nanobots to clean up oil spills and accidentally programmed them to recognize the wrong kind of organic molecules, so that they specifically target living things. Fortunately, he figures this out before they are released and shuts the project down. Unfortunately his boss is Stupid Evil enough to want to restart it as a weapons project.
  • In the Tales Of Tomorrow episode "Red Dust", space explorers who have just visited a once-populated world overrun by Red Goo discover that the pink crystalline "dust" has infested their ship as well.

  • The music video for "Nanobots" by They Might Be Giants involves swarms of little yellow robots turning against their creators and taking over the world before turning it into one big yellow robot. The song is a metaphor for parenthood, with the nanobots representing children.


    Tabletop Games 
  • Centauri Knights, a far future/Humongous Mecha sourcebook for Big Eyes, Small Mouth, takes place on a dead alien planet colonized by humans. According to the Game Master information in the back, the reason the planet was vacant was because an ancient war resulted in a Grey Goo superweapon accidentally being unleashed upon the planet (the game even explicitly uses the term "Grey Goo" to explain the phenomenon).
  • Dungeons & Dragons:
    • A green slime converts anything it touches into more green slime. (Except stone, which is immune to it, and wood is more resistant than most. It dissolves metal very fast, however.) Fortunately, it's immobile, so you can avoid it if you just stay away from it.
    • Clockwork horrors, introduced in Spelljammer, are tiny mechanical beings that methodically and very efficiently scour areas of metal, which they use to build more clockwork horrors and continue the cycle. They leave stone, soil and organic material alone, but if left unchecked can easily devastate entire countries or even strip whole worlds of worked and unworked metal, killing anything that interferes or that the adamantine horror directing the swarm considers a threat. They'd actually consumed their home planet and were effectively trapped there, until the neogi made the mistake of visiting, allowing the horrors to hijack their spelljamming vessels and spread across the crystal spheres.
  • In Eclipse Phase, Grey Goo swarms are among the nastier surprises left behind by the TITANs. There are various types ranging from regular roving disassembler swarms covering much of Earth That Was to the rather more... artistic fractal bombs, which restructure matter into interesting fractal patterns as they spread (nobody is entirely sure why. Presumably, their AI creators simply liked the look...). Their presence is basically the setting's primary Godzilla Threshold... if nanoswarms are involved, even the heroic factions will tend to break out the scorched-earth type weaponry, collateral damage be damned. And then there's "Creepers", swarms of floating black bubbles that are theorized to be femtobots, if ordinary grey goo wasn't scary enough.
  • The End of the World has the "Nanopocalypse" scenario in its fourth book Revolt of the Machines, where a swarm of nanobots originally developed to destroy cancer cells starts consuming everything carbon-based, including trees, asphalt, soil, and people. It's among the bleakest of the scenarios in the book or any other books — not only is almost all of the Earth left a lifeless desert of inorganic dust in the span of about two weeks, what remains of humanity lives in the Antarctic, as the nanobots can't stand the cold. Even then it's implied that there aren't enough renewable resources to go around, leaving humanity — and all life on Earth — to slowly die a cold, lonely end.
  • GURPS: Gray Goo is discussed in GURPS Ultra-Tech in a section on Von Neumann machines, which points out the waste heat of the goo eating a planet is likely a more pressing threat than being eaten by it. On the upside, they require extremely high levels technology and are expensive to make; on the downside, some versions might be able to fly or travel through space.
  • Lancer: Called Greywash in-universe, outbursts of grey goo are not unheard of, and enough have come to pass from printer sabotage and actual nanotech warheads that Whitewash nanite mixtures have been developed and included with regular fire supression systems. Meanwhile, HORUS - haven of unorthodox and horrifying thinking it is - weaponized it in unusual manners by developing the Balor pattern group, which is essentially The Worm That Walks made out of hungry, barely-controlled nanites. While utterly unarmored and very slow, Balor mechs are incredibly difficult to bring down thanks to their fluid composition, constant reconstruction and the fact they can just eat the surroundings (including enemies) to restore themselves in the heat of battle, and getting too close will mean getting Eaten Alive within moments.
  • Nova Praxis: The technophage is a Grey Goo substance that occasionally builds larger and meaner war robots instead of more goo. It started as a nanotech weapon with an off-switch that didn't work, and went on to render Earth uninhabitable.
  • Numenera: At least one (and quite possibly several) of the ancient civilizations made extensive use of nanotechnology, and feral, out-of-control nanobots remain common and widespread in the setting's present.
    • The Iron Wind is a natural disaster (insofar as anything in the setting is truly "natural") that takes the form of vast red sandstorms filled with microscopic, airborne nanites. These nanites are badly malfunctioning (the corebook outright refers to them as insane) and chaotically reshape anything and everything they come across, landscape, machine and creature alike. Living beings caught in the Iron Wind are reshaped into writhing, malformed monsters and usually die soon afterwards, if they aren't outright disassembled.
    • Much more harmless nanites are also fairly well integrated into the ecosystem. They fill similar niches to organic fungi and bacteria, and generally go beneath most people's notice.
  • Pathfinder:
    • The main game has stats for this as a monster, right down to the name. It's considerably dangerous, able to rapidly devour characters (and their gear!) in its space, infest a single target to devour them even faster, and disperse itself to hide from pursuers. And as a swarm, its immune to weapon damage and targetted spells, meaning depending on your party composition you may have a hard time hurting it at all. (Incidentally, this isn't a case of A Wizard Did ItPathfinder Grey Goo is an actual cloud of high-tech nanomachines. It's assumed to come from Numeria, where an ancient crashed spaceship left a bunch of high technology scattered throughout the landscape.)
    • Starfinder has the Assembly Ooze, runaway nano-fabrication units that thankfully do not grow uncontrollably (and only rarely make more of themselves), but instead turn inorganic matter they eat into whatever they were programmed to make. They may seem harmless (unless you happen to be an android or other robotic lifeform), or even beneficial, until one gets loose in your ship and tries to turn the engine into a pile of laser rifles.
  • Shadowrun: Discussed. Nanotech became very pervasive in 4th edition, and the Grey Goo concept is brought up, only written off as "unlikely to ever come to pass" and "an urban myth" by some of the (legit) top scientific experts in universe. Ultimately Averted as even when nanotech starts to fall prey to hostile A.I., it's shown that it isn't capable of destruction on anywhere near this scale, though it still proves to be very dangerous.
  • Star Wars Role Playing Game: In the supplement The Unknown Regions, the Mnggal-Mnggal is described as something like a naturally-occurring, organic variant of Grey Goo. It is sentient, and able to infect any form of matter, as well as take control of creatures as "zombies". Its origins are unknown, and it's likely biological.
  • Warhammer 40,000: Virus Bombs work on a similar principle to the Red or Black Goo scenario noted above. They utilize something called the Life-Eater virus, which consumes everything organic on a planet and leaves behind massive, highly flammable swamps and gas clouds. A follow-up series of incendiary missiles ignites a planet-wide firestorm that scours any remaining life from the surface, leaving nothing behind but a glowing, lifeless rock. The Imperium uses them in dire situations when a problem can only be solved by destroying a planet. For added Nightmare Fuel, note that the Life-Eater is absolutely in the Chaos God Nurgle's wheelhouse. Many of those who have the authority to use these world ending protocols have wisened up, and will prefer to use a Cyclonic torpedo instead.
  • Yu-Gi-Oh!: Cards in the Graydle archetype fall under this. The Graydles themselves are a race of parasitic, alien, metallic Blob Monsters which assimilate other living creatures that come in contact with it, which is reflected in gameplay by allowing their player to take control of an opponent's monster when the graydle is destroyed and sent to the graveyard. The art of cards like Graydle Cobra and Graydle Alligator show the infected creatures bodies gradually decomposing and being converted into even more grey goo while their syncro summon monster, Graydle Dragon, shows the various creatures being combined into one large monstrosity with the Graydle's matter becoming an armored, mechanical hide over most of the body.

    Video Games 
  • AI War 2: The appropriately-named Nanocaust is a nanite plague capable of infecting and spreading from spaceship to spaceship like a plague, and forming hives upon planets to consume everything in them for the purpose of more reproduction and consumption. It's unknown where it came from (both aliens and renegade humans are suspected), but even the AI has problems handling it; the description mentions it's the sort of rampaging threat that usually keeps it busy outside the galaxy with its back turned to you.
  • The plot of Blam Machine Head starts after a programmer at the world's biggest manufacturer attempts to inject himself with nanomachines to remodel his physique, causing the nanomachines to go airbornes and kill anything not matching his DNA.
  • Brawlhalla in the backstory of Barraza, it's described how Meyer's Baby Food Corporation attempted a desperate move on a rogue agent's hideout by deploying a self-replicating nanobot cloud on them. These nanobots bricked anything that relied on computer circuitry... which in 2150 was everything. The nanobots were supposed to go inert after 20 minutes, but for some reason they didn't. The end result was the Mad Max-esque post-apocalypse world that Barraza comes from.
  • Tiberium in the main Command & Conquer series is a crystalline substance that, over the course of half a century, drastically alters Earth's climate and mutates its life forms as it spreads across the planet. Tiberium Wars reveals that not only is Tiberium an extremely valuable resource, it's used as a form of Hostile Terraforming by the alien Scrin, who seed planets with it, wait for the natives to wipe themselves out fighting over the stuff, and move in to harvest once everyone who could resist them is dead.
  • One of the possible upgrades for your Alchemy Labs in Cookie Clicker is called "Beige Goo" According to the description, it turned three whole galaxies into cookies.
    • If you bake enough cookies, the news blurb claims that the universe itself has turned into cookies to the molecular level.
  • In the intro cutscene of the video game Deus Ex: Invisible War, a terrorist employs a "Nanite detonator" in Chicago, destroying the city. And in the first Deus Ex, the Gray Death is revealed to be an artificial plague.
    • In Invisible War, there are also "nanite swells" — clouds of nanobots whose origin isn't entirely clear, but which present a serious environmental hazard and are responsible for the poor health of people forced to live outside protected cities. It's never made entirely clear if these are actually self-replicating or just the remains of weapons or experiments used during The End of the World as We Know It.
  • A possible story line from Duskers talks about the gray goo possibly wiping out life in the universe, or just within the Drone pilots area of operation.
  • The Chrome in Fortnite came out of nowhere, swiftly 'chromifying' the Island and most of the Seven. Players can spread it themselves using 'Chrome Splash' items, and even 'chromify' themselves, allowing them to transform into metallic blobs capable of phasing through walls. As a result, the Island's population have evacuated to blimps and flying cities to prevent the spread.
  • The God Eater series has Oracle Cells, single-celled organisms that seek out and consume compatible matter to grow and evolve. What matter is "compatible" differs on a cell-by-cell basis known as "bias factor", and everything on Earth is accounted for (except, oddly, water). It's not just a gooey tidal wave though: when a cluster of Oracle Cells can get a pile of the right compatibility to form, you get an Aragami, a monster who goes around eating matter to distribute it to its constituent cells (which are still trying to consume each other, resulting in a constantly-evolving beast). Pretty much the only reason humanity hasn't been wiped out completely yet is because these Aragami try to out-Darwin each other just as much as going after raw material, but Fenrir is still in a race against time against a nightmare scenario of an Aragami capable of adsorbing all others forming. So far they've only been able to delay this, by having their God Eaters destroy the core cells, causing all Oracle Cells in an Aragami to lose cohesion and start from scratch.
  • The RTS game Grey Goo (2015) has you-know-what as one of the factions. Apparently it was originally designed by humans to explore space, but its programming got corrupted somewhere and now it just attempts to consume all before it. Though eventually it is revealed it is attempting to consume all before it for a reason and not just due to programming corruption — it's a desperation move to build up an army against an attacking alien intelligence.
  • Provides the backstory and setting for Hawken. In the endless Corporate Warfare on the planet Illal, one of the three dominant Mega Corps collapsed, triggering a self-replicating nano virus that converts the environment into a labyrinth of patchwork metal—known as the "Giga Structure" and "Hawken Virus." At the time of the game's launch, the virus covered a third of the planet.
  • In Hostile Waters: Antaeus Rising, the "alien" antagonists have a Disassembler cannon which fires nanites that are programmed to rip apart matter on a subatomic level. This avoids the usual grey goo problem of endless replication, as the nanites just run out of steam, while still producing similar destruction. It fires at a city and reduces it to mush. It's up to you to blow up the cooling radiators before it fires its third salvo and destroys Central, the world capital. Once you do that, the next shot blows it to hell and spreads disassemblers throughout their base.
  • A variation of this occurred in Horizon Zero Dawn - a line of robotic soldiers that consumed biomass as fuel (supposed to only be in emergency situations) and could self-replicate was one day stricken with a glitch that made them ignore all commands and go rogue, and due to their highly advanced coding and the fact that the CEO of the company that created them specifically told the engineers to not install a backdoor, it was nigh-unstoppable and these rogue robotic soldiers consumed all organic life on the planet in less than two years. The title is derived from the in universe project meant to not only shut the rogue bots down, but to also bring life back to Earth through a highly advanced AI system.
    • How did the aforementioned bots consume their biomass? They had nanites of their own, which stripped the biomass and carried it back to the bot. And sometimes they targeted humans.
  • In the Mass Effect games, you can find a planet called Zaherux, which is covered with seas of silicon. The flavor text mentions that a popular extranet meme says that the oceans are actually a huge swarm of 'disassembler' nanites.
  • Part of the plot of Mighty No. 9. The Final Boss, Trinity, was accidentally programmed to absorb everything it can, and it does. Which results in it absorbing nearly an entire building, transforming it into the game's cube-like equivalent of nanobots.
  • In Smoke's ending in Mortal Kombat: Armageddon, the power of Blaze causes his nanobots to go into overdrive, consuming all of Edenia and replacing it with a sentient mass of grey goo that calls itself Smoke.
  • Noita:
    • Draught of Midas converts any solid material into Gold on contact but is not consumed in the process. If a Fungal Shift converts Gold into Draught, every pixel of gold becomes the seed for an exponentially growing mass of Draught which will convert every non-liquid material into more of itself.
    • Acid converts solid substances into a large volume of Flammable Gas but is consumed in the process. Fungal Shifting the Gas into Acid causes any free Acid to explode in volume, faster than even Draught.
    • Void Liquid converts any Toxic or Fungal material into more Void Liquid on contact. This isn't an issue for most of the game world except for the Overgrown Caverns biome. Aside from the large amounts of free-growing fungus, all of the soil in this biome is considered Fungus. Even a single pixel of Void Liquid released near the top of the biome will wipe out a massive swathe of terrain.
    • Concentrated Mana rapidly converts any water it contacts into more of itself and dissolves all metals. While the potion's effects make this entirely beneficial for the player, the potential ecological consequences of converting the entire water supply of a region into a liquid that does not evaporate or freeze would be dire.
  • Biological version in Outpost 2: Divided Destiny. A terraforming microbe runs wildly out of control, breaking down organic matter, among other things, and forcing both colonies on the planet to try to evacuate-one of the rare versions in which the Goo truly is unstoppable, though one colony can delay it briefly, and the omnipresent threat during the campaign.
  • Parasite Eve features massive amounts of Pink Goo. The Big Bad is actually a Patient Zero infected with intelligent pink goo by accident. Every enemy in the game was created by the pink goo. If you go on to the Chrysler Building in the EX game, the building itself is infected with the pink goo (which is the in-world reasons that mode has random maps) and pink goo is literally everywhere.
  • Seedship: Alien nanobots can potentially attack the ship, and the player has to determine how to handle them.
  • In Sid Meier's Alpha Centauri, one of the Special Projects shows the video of several containers placed on the site of a battle, littered with debris and dead bodies. The containers open, releasing nanites that look like glowing goo. They proceed to consume everything in sight, including the dead, and use the materials to create a brand-new Hover Tank.
    • Miriam Godwinson also very specifically warns against this type of scenario:
    Already we have turned all of our critical industries, all of our material resources, over to these...things...these lumps of silver and paste we call nanorobots. And now we propose to teach them intelligence? What, pray tell, will we do when these little homunculi awaken one day announce that they have no further need for us?
    Sister Miriam Godwinson, "We Must Dissent"
  • The last "secret" life form class on SimEarth, robots (unlocked by bombing a Nanotech-class city, fittingly enough), are very well-suited for survival. By this, it means that they reproduce rapidly, they can live in any habitat — even the ocean — and thus can spread across the entire map with little effort, competing against organic life can't even be called a competition, and — oh yeah. They're immune to disasters, even ones activated by the player. All organic life on your planet will quickly go extinct when these guys show up.
  • The Vasari from Sins of a Solar Empire, who specialize in Nanotechnology, have ships that are able to throw blobs of destructive nanobots at enemy ships.
  • The Tarr in Slime Rancher are an organic example. They are formed when too many slimes eat too many plorts from other slimes and all they do is drag slimes and meat like the player and chickens and eat them. If they eat a slime they produce a copy of themselves.
  • The same idea on a much larger scale happens in Star Control II. The Slylandro, a planet-bound race, purchase a space exploration probe from some interstellar traders. They can afford only one, so they set its "replication" priority extremely high, causing it to attempt to break down everything it encounters into component compounds to build new probes. By the beginning of the game's timeline the quadrant is already swarming with these things, and it's projected that they'll continue to grow exponentially until they devour the galaxy unless you find a way to stop them.
  • The Stellaris story pack Distant Stars centers around a deactivated Portal Network that connects to the "L-Cluster," a clump of planetary systems beyond the borders of the known galaxy. What happens when you reactivate the L-Gates to reach it is randomly chosen at the start of a new game, but all are different snapshots of the same Gray Goo scenario.
    • The most common outcome is the release of the "Gray Tempest," a swarm of crazy-strong nanobot starships that wiped out the L-Cluster's original inhabitants and will try to bury the galaxy proper in nanomachines. If this happens, the first thing you get out of the L-Gate is a degraded recorded message from the lost inhabitants of the Cluster warning you to NOT open the gate. The good news is that destroying the Gray Tempest's control hub and claiming the L-Cluster nets valuable strategic resources, and any worlds compromised by nanomachines can be easily terraformed into any climate type desired.
    • Another outcome unleashes a cluster of "L-Drakes," a variant of ether drake, instead of a starship swarm. These are nonaggressive unless attacked, but if that happens, there's the Robotic Reveal that these creatures are comprised of nanomachines — they're the Gray Tempest after it's calmed down from Kill All Humans mode and assumed more natural forms.
    • A third outcome has your survey ship discover a bunch of dead worlds... and a single individual of your species walking on an airless planetoid. This is Gray, the Gray Tempest coalesced into a single sapient entity, who has grown bored enough to be willing to join your empire as an immortal specialist, or he can shapeshift into a warship that will eventually reconstitute itself if destroyed.
    • The final outcome is the discovery of the Dessanu Consonance in the L-Cluster, an advanced and friendly civilization... unless you ask about nanites, or enter a certain forbidden system that turns out to contain a nanomachine control hub. They too are the Gray Tempest, grown remorseful about the eradication of their creators, leading them to atone by rebuilding the L-Cluster into Gaia Worlds and taking the forms of the people they destroyed.
  • The True Final Boss of Super Robot Wars: Original Generation, Septuagint, can be seen as this. It may be more of purple crystals, but its directive is clear: exterminate the whole world by consuming anything to come to its path, and it can even make crystal-based duplicates of things it has consumed.
  • A grey goo like attack is possible in Supreme Commander 2. The Cybran Nation can upgrade their engineers to have weapons, by doing this and building nothing but engineers you will get an ever growing blob of engineers that will automatically shoot every enemy in sight and use the remains to build more engineers. Full instructions here.
  • Grey goo missiles called the "Nano Virus" are a high-level planetary siege weapon in Sword of the Stars. It is amusingly classified as a bio-weapon, meaning you have to go through several tiers worth of gene modification to access it. The Nano Virus is harmless to organics, but the planet's industrial output will be heavily damaged and it will wipe out an AI rebellion as if they were living creatures hit by a regular bio weapon. It is the only bio weapon that will affect the Zuul, since their machinery is made of the same metal as everyone else's.
  • Tasty Planet is a game based on Grey Goo where a cleaning agent gets bigger and bigger as you guide it through the levels starting on a Petri Dish until it eats the planet, then the solar system, galaxy, universe, space and time! Then it explodes and everything starts over.
  • Torment: Tides of Numenera: The Iron Wind from the tabletop setting makes a cameo; one of the people you meet has some of it caught in a jar. If you mess with the jar too much, it breaks, and although your character usually just comes back from the dead, this one they don't come back from.
  • Xenoblade Chronicles 2 gives a more benevolent example with the Cloud Sea. Instead of water, it's comprised of self-replicating reconstructor particles with the same density as water (but spread out over the surface) to help the world recover from Klaus' experiment. What makes it benevolent is that it doesn't just use whatever odds and ends it can find (like the Titans). Instead, it uses whatever's been inert for too long as material to rebuild any technology from before the experiment for the new world he created as The Architect.
  • The Eldritch Abomination Deus from Xenogears is upgraded from a simple biological weapon into a living mass of Grey Goo by the game's Big Bad Krelian through nanomachines.

    Web Animation 
  • gen:LOCK: The Union mainly rely on nanotechnology to quickly destroy organic matter in their path - neither humans, animals or plants are exempt from this. It's due to this that The Vanguard spent the next four years on the defense prior to the use of the titular technology. Doctor Weller eventually figures out a way to disrupt the nanotech swarms by mimicking the signals that Union troops and symapathizers use to mark themselves as being friendly, which effectively turns the tide of the war from a slow retreat to a stalemate.

  • 21st Century Fox points out the concept is actually kind of stupid here.
    "You know, if the people who think that self replicating nanites will accidentally escape from ideal, sterile laboratory conditions and turn Earth, from the tropics to the Arctic, from the oceans to the deserts, into a glob of grey goo, ever read the instructions of a packet of seeds, they'd all sleep better at night."
  • In Freefall, Dr. Bowman points out that if robots have human desires as their sole and singular goal, as well as the ability to reproduce, then what you wind up with isn't too far off from grey goo.
    Dr. Bowman: Good news if you're a human. Bad news if you're anything else.
  • Nobody Scores!: When all you have is a jar of nanorobots, everything looks like a problem best solved by the application of nanorobots.
  • Schlock Mercenary:
    • Hostile nanoswarms are so common that there's standard-issue tactics and equipment to stop them; people worried about nanobot infection drink nanotech-fighting chemicals to control them, "nanofilm" is routinely employed to control rogue nanobot swarms, and worst comes to worst, the nanobots will be isolated by ubiquitous AI with gravity-control technology.
      Assassin Flamb: We've all been drinking Nanneze like it was Ovalquik.
      Tagon: Eugh. That stuff'll kill you.
      Employer: The Nanneze, or the Ovalquik?
      Tagon: Both.
    • The comic does point out one of the biggest weaknesses of nanobots: Extreme heat. Even when they have evolved plasma shielding, any reasonably dangerous level of heat will overwhelm any defenses the nanites have and cause their inner workings to warp and fail. If a gravitic-enabled AI isn't around to help, it's common to bust out the plasma weapons on wide spread to handle hostile swarms. For bonus points, most Powered Armor in the setting can handle fire without too much difficulty, so you don't even have to worry about your own men. Unarmored civilians, however, can at best hope to get off with third degree burns to their entire body. Good thing medical technology has made a few advances...
    • Sergeant Schlock has been mistaken for grey goo a couple times. And to be fair, they're not that far off, and when pitted in a who-eats-who duel against the actual stuff he was evenly matched.As in...
  • Vexxarr has the Locutrons create a Grey Goo while making a new startship paint. This Grey Goo succeeds in spreading across the entire universe, only to to send back a sentient avatar from the Natural End of Time to Set Right What Once Went Wrong.
    Grey Goo avatar: No, isolate. That way is behind me. It is true I consumed the cosmos. I spread my body until I was the very light that speckled the night sky. I became all and all became one. And then I was alone. Do you know what it means to be literally alone in the universe? To wonder what's out there and know without question that the answer is me?
  • Waterworks has black goo of the biological variety. At first assumed to be a corrosive liquid, upon closer inspection it's revealed to be composed of cells that slowly devour anything organic they come in contact with and are capable of evolving.
  • xkcd:
    • This page jokes about how IPv6 is perfect in that the nanobots will only be able to devour about half the planet before they run out of addresses.
    • Another comic on "Scary Names" noted "Grey Goo" might not sound scary, but is something as terrifying as "Bird flu" and "Demon core."

    Web Original 
  • In the late 20th century of the Chaos Timeline, nukes are scrapped because nanobots made them obsolete. The so-called Braunschleim scenario is the casual armageddon scenario everybody fears. On the eve of World War III, this fear urges a bunch of Playful Hackers to seize control over the military and the rest of the world, in order to prevent the danger of nano annihilation.
  • In Orion's Arm, there are many kinds of self-replicating nanomachines that are all categorised as goo, with grey goo among them. One outbreak of grey goo caused massive damage to humanity early in the setting's history, and this event is known as the Technocalypse. However, the relatively realistic nature of the setting means that dangerous goo is far from unstoppable, being vulnerable to extreme heat, extreme cold, loud sounds, radiation and many other things. The Technocalypse was halted thanks to the usage of blue goo (nanomachines created specifically to neutralize grey goo). Humanity would actually have been able to recover if it wasn't for the subsequent actions of GAIA.
  • SCP Foundation:
    • SCP-009 is red colored water that freezes when warm and melts when cold and turns normal water into more of itself. The number is likely a reference to ice-nine from Cat's Cradle.
    • SCP-1689 is a Bag of Holding that distributes endless potatoes. Excavations into its interior imply it's a version of Earth that got overrun by a self-replicating potato apocalypse.
    • SCP-204 is a downplayed example, as the cloud of nanomachines usually only destroys animals (including living people) to serve as fuel. But SCP-204 is still ranked at the highest threat level possible, probably because from organic matter to anything else is a quick jump.
    • SCP-3049 is a gas oven that creates an entire miniature universe inside itself. In most cases, one planet within this universe will develop sentient life that then creates nanotechnology, eventually leading to a Grey Goo event that transforms the entire universe into an apple pie in a glass dish.
    • SCP-3280 is a sapient water-like substance that converts any water it touches into more of itself, and which seeks out humans to force itself into, killing the victim from within. And it managed to take over the Earth's water cycle. The protagonist reading the SCP entry turns out to have an instance of SCP-3280 within themself, and as they fall against a window, they realize that the rain outside isn't just any rain pounding on the window, it's falling up towards them, as the equally killer water inside of them expels from their throat.
  • The Creepypasta Achilles IV is about a starship thst picked up an unknown substance (later discovered to be a type of fungus) that converts other forms of matter into more of itself, which then forms into a cityscape. The protagonist details how it ate the rest of his crew and started gnawing on the structure of the Achilles IV during the remainder of his trip to Alpha Centauri.

    Western Animation 
  • Adventure Time: The short "Have You Seen the Muffin Mess?" has Princess Bubblegum accidentally creating nanites that threaten to turn all of Ooo into muffins.
  • Code Lyoko
    • "Amnesia": XANA infects nanobots from a class as an infestation to cause massive amounts of memory loss.
    • "Marabounta": Jeremie tried to create a virus that would destroy XANA's monsters, using Franz's Hopper's journal and basing it off African army ants. At first the huge blob-like monster seemed to work, attacking and devouring XANA's minions. Then something went wrong, and it tried to attack Aelita. Jeremie realized too late that her connection to XANA was causing it to mistake her for one of the monsters, but by then it was out of control and growing larger by the minute, threatening to consume all of Lyoko. (Leading to one of the most chilling scenes of the series to date, Yumi trying to protect Aelita, only to be devirtualized when she was Eaten Alive by the thing.) Fortunately, XANA, who at that point needed Aelita alive to complete his plans, instructed his monsters to help the heroes, and due to the brief alliance, they bought enough time for Jeremie to program an anti-virus that eradicated it.
  • Futurama:
    • "A Clockwork Origin": Professor Farnsworth's nanobots quickly start evolving into more complex forms after being turned loos to purify the new planet's water. They eventually emerge from the waters as a wave of macroscopic "trilobots", which swarm over and quickly consume the Planet Express spaceship and the crew's cabin and supplies.
    • "Benderama": Parodied. Thanks to an invention of the professor's that can make two half-sized duplicates of an object using consumed matter. Bender integrates the device into himself and starts making half-sized duplicates of himself by eating random objects. Each of the duplicates has the same ability. Eventually the replica-Benders become small enough to manipulate atoms directly and start consuming the planet's mass. Eventually, though, the quintillions of nano-Benders get fed up with doing work for Bender and leave the planet. At one point in the episode, Bender says the trope name word-for-word.
  • Gargoyles: "Walkabout": An artificially intelligent nanite mass begins a grey goo surge and the only way to stop it is to communicate with it in the Dreamtime. Once that was achieved, the mass was convinced to stop by interesting it in learning about human law and order and it bonded with Dingo's power armor for that purpose.
  • Godzilla: The Series: One of the first Monsters of the Week is a colony of self-replicating petroleum-eating nanomachines that, inevitably, goes out of control and turns into a Zilla-sized shapeshifting blob on a feeding frenzy.
  • The Incredible Hulk (1982): One episode involves a scientist bioengineering a Blob Monster that could eat literally anything except the special glass of its container, and would get bigger the more it ate. Of course the glass breaks and it starts eating Gamma Base. Fortunately, it turns out that the one thing it's allergic to is gamma radiation, which the Hulk constantly emits.
  • Justice League Unlimited: "Dark Heart" deals with alien nanomachines that are in the process of taking over Earth this way. Their species appears to be made artificially for a war from fifty-thousand years ago, and is meant to consume every planet they're sent to, spread to some other planets, and repeat until they're all dead.
  • My Life as a Teenage Robot: "Party Machine": An army of tiny multiplying aliens invade Earth, which Jenny and Brad defeat with a vacuum cleaner-like tool created by Dr. Wakeman to defeat them.
  • The Powerpuff Girls (1998): "Nano of the North" features a swarm of Grey Goo nanobots dropping from a raincloud and destroying Townsville, though the bots thankfully ignored living creatures. Since the girls are too big to fight them (it only ends up with them eating their clothes) they are shrunk to their level to fight. When they are overpowered by the girls, the nanobots fuse into a relatively-Humongous Mecha... which is just as big as an insect, allowing Professor Utonium to crush it under his foot.
  • The "annoying replicating electrical prankster" story is practically its own sub-trope; part of this can be laid at the feet of writer David Wise, who was notorious for recycling scripts, plot elements and the like between shows. The Transformers episode "Kremzeek!" involved a highly specialized electricity eating spark creature, splitting into new copies of itself as it ate more and more current. For Teenage Mutant Ninja Turtles (1987) cartoon, it was called "The Big Zipp Attack"; in Mighty Ducks: The Animated Series it was "Zap Attack".
    • Ben 10 (which did not have Wise as a writer) had the imagination to not name it after the creature: instead of something like "The Megawhatts Attack", the critters are first encountered in Tourist Trap. (Unusually, the Megawhatts go on to be a seldom-seen but established part of the setting. They're actually an alien race called Nosedeenians, and make a return appearance in which Ben and company had to save them from villains who were kidnapping and enslaving them as a power source. Ben later gains one as an Omnitrix form, which he calls Buzzshock.) It's not as obligatory as the "Fantastic Voyage" Plot, but watch enough cartoons and you'll know it by heart.
    • Transformers: Prime would later return to this plot when it introduced the Scraplets (adapted from The Transformers (Marvel)).

    Real Life 
  • The scenario was first proposed by Eric Drexler. He has since dismissed it as unrealistic as it's much easier to create a bunch of tiny dumb robots that receive their instructions from a central computer (that can be disabled if it malfunctions) than it is to create tiny robots that know and are capable of doing everything they need to make copies. The dumb nanobots should serve any purpose we'd need smart nanobots for, so any grey goo scenario would have to be created maliciously.
    • There's also the thought of police nanobots designed to keep the grey goo in check, a concept called "Blue Goo".
    • Jan Hendrik Schön's research seemed to show that a gray goo event was possible, but then, well, the truth about his research came out.
  • Life itself has spread to every conceivable corner of the Earth (that we have been able to check so far) in the last 4.5 billion years and readily converts non-living matter into living matter through its inexorable reproduction. It is also really, really difficult to truly sterilize anything. This is sometimes referred to as the "green goo" scenario
    • Hela cells (an immortal cancer cell line used in biomedical research) act like Grey Goo, in that they're notoriously hard to kill off and often contaminate and convert non-Hela cell lines. Hela is such a problem in many labs that, if the lab wants to use Hela, it cannot use any other cell line in fear of compromising good science. Incidentally, "Hela" is short for Henrietta Lacks, the name of the woman the cancer originally mutated from; this is human grey goo. If you want an idea about how bad this made things, Hela cells were used before DNA testing could prove that the cell lines were pure. Once the problem was discovered and announced, the microbiology community was stunned. Many were disheartened to find that the experiments they performed were indeed tainted. Decades of research had to be thrown out and retried. This doesn't even take into account all the cell lines that were probably made extinct and the samples disposed of so, thus, they could never be retested to be sure they went off as intended.
    • On that note, cancer itself. It's a cell that refuses to stop dividing, and the errors that led to the situation cascade, resulting in an ever-growing — and worse, ever-changing, making it devilishly hard to treat — mass of aberrant tissue that eventually sucks all the nutrients from the body. It can even spread to other body parts, in a process called "metastasis." Of course, the patient usually dies before their whole body is transformed into mutant cells.
  • A nuclear chain reaction could be considered a subatomic version of Grey Goo, in how it spreads from atom to atom, splitting each one so it ejects neutrons that split other atoms and thus perpetuate the process.
  • Another, really freaky example from the world of nuclear physics is the strangelet, a particle of strange matter (that is, matter made from strange-type quarks) that's hypothesized to be able to convert normal matter into strange matter just by coming into contact with it. The converted particle then immediately does the same to a neighboring ordinary particle, and thus doom takes its course. If such a thing were to happen on Earth, it would quickly and irrevocably turn our pretty blue planet into an incredibly lethal ball of strange matter, and there's nothing at all we could do about it.
  • Prionic brain diseases such as mad cow operate like Grey Goo for the nervous system, as abnormal proteins cause adjacent protein molecules to be reconfigured into more of the same.
  • A more harmless, benevolent version of Gray Goo involves theoretical space exploration. It's believed that once we acquire the right technology, we'll be able to create interstellar probes out of nanobots. Once they land on a planet they'll convert as much matter needed into ten more nanobots and fire them out into space. However, others have speculated that such a system would devolve into a straight version of this trope given time (Carl Sagan argued that if they were viable this would already have happened); in fact swarms of so-called Von Neumann probes are an entire subgenre of this trope, including the deliberately malicious version often referred to as Berserkers.
  • Another nuclear physics example (though slightly stretching the idea of grey goo): a true vacuum. If our universe is a metastable false vacuum, then at any time a true vacuum could spontaneously appear, and expand out at the speed of light. It would turn everything it envelopes into new forms of matter (and of course destroy everything in the process). Right now we can't rule this out, and perhaps a true vacuum is heading towards us right now...

Alternative Title(s): Gray Goo