Diseases are scary. However, germs are rather small. This leads to a bit of a problem. You see, scary things can make good villains, but you need to be able to see them.
This has led to writers coming up with two different but functionally similar solutions to this problem. Either have the microbe get really really big or have the hero get really really small. This runs almost entirely on Artistic License – Biology and the most extreme form of Square-Cube Law.
In many cases, the wee beasties aren't disease germs, but simply single-celled organisms; favorites are amoebae and paramecia. In other cases, they're normal parts of the human body; antibodies, or blood cells.
Some varieties of Mega-Microbes can overlap with the Blob Monster. More often than not, they will be portrayed as Monstrous Germs with eyes, jaws, pincers or tentacles. Compare Proportionately Ponderous Parasites.
- In Cells at Work!, everyone is microscopic, though some bacteria and other pathogens are depicted as larger than the human cells (in real life most bacteria are much smaller than eukaryotic cells).
- Moyashimon: The protagonist can perceive and interact with microbes as if they were macroscopic and sapient creatures.
- In Mushishi, most mushi are giant magical microbes.
- Yu-Gi-Oh!: A card called Giant Germ deals damage and acts like an Asteroids Monster.
- In Benito Jacovitti's sci-fi epic Arcicomiche Stellari, the protagonists at one point are threatened by alien humanoid plants that happen to be single-celled organisms — making them immune to the hero's Disintegrator Ray.
- Disney Mouse and Duck Comics:
- Disney Ducks Comic Universe: In the Don Rosa Scrooge McDuck story "The Incredible Shrinking Tightwad" (currently the page image), Scrooge and Donald are eventually shrunk down to microscopic size due to the effects of a malfunctioning shrinking ray, and are menaced by a horde of microbes.
- Mickey Mouse Comic Universe: In a Super Goof story, a villain uses a ray gun to enlarge animals. In the final battle, Super Goof was pitted against a van-sized amoeba.
- Superman: A Bronze Age Age story deals with a sheltered Bubble Boy who, after seeing that Superman is real, decides that everything on TV is real and escapes to warn the character on a futurist version of The Fugitive that the cop that's chasing him is about to capture him. He tries to trick the kid into killing the other actor to save his career only to end up consumed by one of the kid's white blood cells, as his parents never informed him that exposing his blood to air caused them to grow to blob monster size and he'd scratched himself on a bush earlier.
- An old horror comic deals with an alien seeking the most ferocious creature on Earth but, as he probes the human protagonist's mind, he finds everything offered up (like bears and tigers) to be quite boring, until he picks up on a subconscious thought from the protagonist and teleports them where a truly horrific tentacled beast awaits that the alien quickly photographs then kills. The monster was the cancer infecting his terminally ill wife, only now she's cured.
- The Wacky Adventures of Pedro: One storyline had Pedro and most of the town's inhabitants shrunk to microscopic size and fall into a creek. For the next several issues, "Pedramoeba" had adventures in the microscopic world until the local Mad Scientist scaled everyone back up (and also enlarged a few actual microbes, which was his original intention).
- The Blob (1988): Unlike the original film, this iteration of the Blob is actually the result of a secret government germ warfare project gone wrong. The original experiment was disposed of by being launched into orbit, but it ended up mutating in space and crashing back down to Earth as a macroscopic, predatory Blob Monster that gets bigger as it eats, eventually reaching the size of a bus in the climax.
- Evolution: The Ultimate Lifeform created by the alien ecosystem is a gigantic amoeba-like being that quickly consumes every other organism before bursting onto the surface.
- In Fantastic Voyage, the heroes had to survive being caught in the crossfire of antibodies versus bacteria, "recticular fibers" that clog the intake ports, a direct attack on Grant and Cora by antibodies, and white corpuscles. Inverted though in that the microbes are normal size but the heroes have been shrunken down.
- The Flesh Eaters features the titular micro-organisms joining together to become one large creature.
- Star Trek III: The Search for Spock has a set of microbes that get supersized thanks to the Genesis Effect. Later, they get so big that Captain Kruge gets to have a fight with one of them!
- Choose Your Own Adventure: In some books that involve some shrink-ray device, a few bad endings have microbes (e.g. paramecium, or white blood cells) attach themselves to an object which returns to normal size. In the case of an amoeba, it took Kentucky for breakfast, then Louisiana for lunch. Even at their normal microscopic size, they look very large.
- Into the Jaws of Doom: On the Museum's second floor, you can run into a science experiment gone wrong, resulting in a bacteria that doubles in size every few seconds while pursuing you. If that happens, you will be devoured regardless whichever choice you make — it's a Hopeless Boss Fight and your best best is to avoid entering the science lab.
- In Danny Dunn and the Smallifying Machine, the shrunken characters observe microorganisms swimming in the tiny puddle where they stop to take a drink. One of the kids mistakes them for fish at first glance, then realizes they're far too small for that.
- Galaxy of Fear: The Planet Plague gives Tash an electroscope-thing which she uses to see the virus behind The Virus. It's stated a few times to be magnifying the microbes, but is used more like magic glasses that reveal invisible things — she sees them overlaid over her normal vision and can tell at a glance if someone's covered with them. The viruses themselves seem to swim through the air after people.
- In Illuminatus!, the massive sentient one-celled creature Leviathan is beleived to have been inspired by the xenophyophores discussed in Real Life, below. Robert Anton Wilson and Robert Shea realised an amoeba is practically immortal - if it evades diseases and predators it has no reason or need to die - and wondered what would happen if one grew rather than divided. Over millenia.
- The oldest known example of this trope dates back to a French pulp adventure Une Invasion de Macrobes / The Invasion of the Macrobes published in 1909.
- Italian short story I Macrobi ("The Macrobes") is a particularly silly example. Since microbes thrive in filth, pollution caused them to grow to human size in the future. Now called "macrobes", they have overthrown humans and made them second-class citizens. Growing grapes is forbidden, since they could be used to make alcohol which is lethal to macrobes (apparently alcohol can only be made from grapes). To survive in the poisonous wasteland that is now Earth (and which is kept that way by the macrobes, who like it), humans lost their nose through evolution so they cannot smell the bad odors.
- The Belgian sci-fi/horror book La sortie est au fond de l'espace by Sternberg starts like this. All the microbes start growing, making the Earth uninhabitable in a series of scenes between horror and Black Comedy. For the survivors who fled in a spaceship, it goes From Bad to Worse.
- William Tenn's story "Winthrop Was Stubborn", one of the luxurious pastimes available in the far-future world is getting shrunk to microscopic size to hunt microbes.
- Aliens in the Family: When Spit is sick, he sneezes out some germs that are the size of baseballs. The have faces and can talk.
- Doctor Who:
- The episode "The Invisible Enemy" uses this trope both ways. First, the Doctor sends miniaturized clones of himself and Leela into his own body to root out the sentient space virus that's infected his brain. Second, the virus (which resembles the front half a lobster) is extracted from the Doctor's body and enlarged to human size.
- In "Kill the Moon", the Moon is revealed to be a giant egg for some sort of space dragon...thing, with spider-shaped "microbes" on its surface the size of a large dog. They can still be killed with Lysol, though.
- Used in the Fringe episode "Bound" with a single-celled cold virus grown to the size of a cucumber. Yes, they did call it a "single-celled virus".
- One Muppet Labs sketch on The Muppet Show features Bunsen using a germ enlarger to make microscopes obsolete. The giant germ attacks Beaker.
- The Outer Limits (1995): In "In the Blood", the USAS spaceship Copernicus is exploring trans-space, a newly discovered Alternate Universe which allows for near instantaneous transport between two points in space which would otherwise take years to traverse. Almost as soon as the Copernicus enters trans-space, it is bombarded with gravitons. The astrophysicist Dr. Callie Whitehorse Landau, who has just discovered that she is pregnant, begins to experience hallucinations of her late grandmother, a member of the Navajo tribe who lived her entire life in Arizona. Callie comes to the conclusion that trans-space is part of a gigantic living organism and the gravitons act as its white blood cells. The floating rocks that it also contains are essentially its red blood cells. Her hypothesis is confirmed by Dr. Lucille Kennedy, who has detected a double helix structure in the dark stars found in trans-space. Callie speculates that trans-space was able to communicate with her because she was pregnant and it recognized that there was a new life growing inside of her. Callie and Dr. Kennedy believe that trans-space is the source of all life in the normal universe.
- Star Trek:
- The Star Trek: The Original Series episode "Operation: Annihilate!" involves Puppeteer Parasites that are described as single cells that act as a Hive Mind. In another episode, "The Immunity Syndrome", the Enterprise crew fight a giant space amoeba at least as big as a planet.
- The Star Trek: Voyager episode "Macrocosm" has the crew dealing with giant basketball-sized flying viruses.
- Super Sentai
- The Baomea Mooks of Bakuryuu Sentai Abaranger are humanoid amoeba. Mikela and Voffa, the two monster makers, are also based on amoeba. Dezumozorlya, the Big Bad of the show, is based on a paramecium.
- The Meba, the mooks in Doubutsu Sentai Zyuohger are also humanoid amoeba. Ginis, the Big Bad, is revealed to be a conglomeration of these creatures, which fueled a massive inferiority complex.
- The Ricky Gervais Show: One entry in Karl's diary has him posit the theory that germs will grow so large in the near future that you'll simply choke on them instead of getting infected. It's so outrageous that instead of mocking Karl, Ricky shows genuine concern for his mental well-being.
- Pathfinder: Giant amoebas appear as a kind of monster for the players to fight, and are classified as Small (the same size category as gnomes) oozes. They are explicitly stated to be a mutated version of creatures normally too small to see. They typically live in sewers and prey on rats and other small creatures, but can and will attack humanoids out of hunger. There are swarms of smaller amoebas, whose component organisms, although coin-sized, are still much larger than any real amoeba. Giant amoebas can create amoeba swarms by splitting off parts of themselves or turning their entire body into swarm, while a swarm can fuse into a single giant amoeba.
- Warhammer Fantasy Roleplay: Amoebae of considerable size live within the rivers and swamps of the Empire. They're entirely mindless, often mistaken for jellyfish — or, less charitably, for living vomit — and in most ways act like the regular microscopic kind. They usually stick to the water but will crawl onto land when hungry enough, and will attempt to engulf and digest whichever parts of a larger creature — like a human — they happen to be able to reach.
- BIONICLE: While hunting for the Mask of Life, the Toa Inika encounter some strange monsters that self duplicate when struck and figure out that they are actually enlarged microbes.
- Giant Microbes' toys are this trope (in plush form) and are the former Trope Namer. However not all are infectious microbes. One is yeast, a few are cells.
- The Trash Pack has the team of the Bin-Fections, who are the same size as the other Trashies. This is later expanded into a whole wave, with Series 7 being themed around "Junk Germs".
- City of Heroes has Hamidon, giant single-celled organism and endgame raid boss.
- E.V.O.: Search for Eden: The final boss, Bolbox, resembles a giant algal cell who thinks he's human. In contrast to the natural evolutions of the protagonist, Bolbox took advantage of Martian crystals in order to rapidly mutate.
- Final Fantasy: Giant vaguely-microbial... things are present in earlier games as generic Mooks, and seem to have been abandoned as the series became more "realistic".
- Illusions (1984) involves guiding "amoeba-like creatures" called Gleebs to safety.
- The Legend of Zelda: Ocarina of Time: Morpha's Boss Subtitles identify it as a Giant Aquatic Amoeba.
- Viruses in the Mario & Luigi series. Back in Dr. Mario, these were a reasonable size (bigger than they should be, but still small enough to fit rows of them inside a medicine bottle; also, the trio symbolizing the remaining types of viruses was shown under a magnifying glass at the corner of the screen). In Mario & Luigi: Superstar Saga and Mario & Luigi: Dream Team? They're about as big as a person is and come in armies about 16 strong at a time. They also tend to show up in rather unusual places like deserts, caves, mountains, parks and towns.
- Pikmin (2001): One of the creatures Captain Olimar can encounter is a Goolix. It's a giant unicellular organism at least a foot across (gigantic compared to the tiny Olimar) with a watery interior and two nuclei.
- Pokémon has Solosis and its evolutions, all of which are giant cells. There's also Deoxys, a giant, humanoid space-virus. The latter isn't explicitly un cellular or single cellular; all we know is that it started that way before the Pokemon world changed it.
- Snipper Clips has you sheltering giant, flying amoebas in the "silly science" world.
- Stray: The Zurk enemies that infest regions of the underground city are actually descended from genetically modified bacteria that were originally designed to consume garbage. After the extinction of mankind, they evolved in macroscopic, animal-like predators that can eat basically anything. They retain the common microbial weakness to UV rays, however.
- Temple of Apshai: The Giant Amoebas are masses of gray protoplasm which have a strong solvent effect on living flesh. They range from six to ten feet in diameter.
- El Viento: The third boss is a huge single-celled organism.
- Xenoblade Chronicles 1: These show up as enemies in the Bionis' Interior, and all possess the trait of being highly resistant to physical attacks.
- X Multiply: An experimental ship gets shrunk and injected into a human body to destroy the diseases that are microscopic aliens from within. Said diseases look like the cyber-organic foes from R-Type, complete with a Battleship Raid against some huge multi-part monstrosity.
- Awful Hospital has the toddler-sized virus Dr. Phage and Zoe the protozoan receptionist on staff; there is also a thriving community of bacterians in a corpse-themed world, most notably the grandmotherly Dr. Staph. Celia and her fallen kingdom are mold particles.
- The comic Irritability played with this once, with Chappy bragging about his victory over a giant plankton.
Chappy: It was huge!
Tatanya: Like this? (pictures a building-sized plankton screeching "RAR!")
Chappy: ...for a plankton. (pictures himself grasping that same plankton, now about the size of an apple, and saying "I have u now!")
- Unity has, in the Invasion story arc, a number of sentient single-celled organisms which the colonists end up calling "macrobes."
- This story at the SCP Foundation site, as well as SCP-371.
- DSBT InsaniT: Cell is essentially a giant watery cell with no true body besides his brain-like nucleus.
- Batman: The Brave and the Bold: In "Journey to the Center of the Bat!", Batman is stricken down by a disease during a fight with Chemo (who is being controlled by Brain), and the Atom must miniaturize himself and travel with Aquaman into the Caped Crusader's body to cure him. During their journey, they are are attacked by viruses, and Aquaman telepathically summons a lymphocyte, which he names "Platelet", that he uses as a mount.
- In one episode of Captain N: The Game Master Kevin gets sick and the source of the disease is a microbe called Viroid. In response to this the N Team shrinks down to confront him inside Kevin's body.
- Godzilla: The Series had a gigantic bacterium the Big G had to fight. It could infect other organisms with smaller versions of itself, depending on how large the organism was.
- In the Darkwing Duck episode "Getting Antsy", the antagonist Lilliput shrinks Darkwing down to the size of a germ with his Shrink Ray - and Darkwing convinces a handful of friendly germs to make Lilliput sick. When Darkwing is turned back to his regular size, two of the germs, whom Darkwing introduces as "Blob and Ray", are turned human-sized too. They look like green Blob Monsters, but with recognizable facial features.
- In Futurama, a giant paramecium is the winner of the Miss Universe pageant.
- The Amoeba Boys are a gang of three dimwitted crooks in The Powerpuff Girls (1998). They're about the size of humans, and sort of float along the ground.
- Johnny Bravo episode "The Incredible Shrinking Johnny" ends with an amoeba accidentally enlarged to giant size, which proceeds to chase Johnny and Carl down the street.
- OK K.O.! Let's Be Heroes: In the premiere episode, Carol has to take K.O. into work with her because his usual babysitter Punchin' Judy is "fighting the flu". She turns out to mean this literally, as Judy goes by fighting a giant flu virus.
- Used in an episode of Rick and Morty, which featured Morty being shrunk down in order to go into the body of one of Rick's associates, who has been turned into an amusement park based around the various biological functions and organs, as well as featuring many diseases.
- SpongeBob SquarePants:
- Plankton and his relatives are downplayed examples. While Plankton is easily the smallest member of the central cast, and the entire cast is tiny in comparison to humans, he's still visible to the naked eye of the viewers and the aquatic cast, unless he has to be seen though a microscope for a gag.
- Plankton's pet amoeba Spot is an even more downplayed example. At the size of a head of a nail, he's even smaller than Plankton (in his first few appearances anyway), but is visible to the naked eye nonetheless.
- Superman: The Animated Series featured a brief appearance by ameoba enlarged to human size in the episode ("Monkey Fun") that introduced the giant ape "Titano".
- SWAT Kats had a legion of gigantic purple bacteria monsters in its second episode, "The Giant Bacteria". The trouble is, they didn't much look like germs, possessing eyes, mouths and a definite torso shape with arms and legs, due to the first one having originally been an ordinary guy (more or less) who gets mutated by Mad Scientist Dr. Viper.
- The giant amoeba Chaos carolinense, which can grow to sizes of up to 5 milimeters, big enough to be seen by the naked eye!
- The largest known single-celled lifeforms on the planet are amoeba-like protista called xenophyophores. They run about ten centimeters across. Small by monster standards, but positively kaiju-sized by cell standards. They are found exclusively in the deepest parts of the ocean.
- Another very large single-celled organism is Valonia ventricosa, the bubble algae, which averages 1 to 4 centimeters across.
- Nowhere near massive, but the intestinal protozoal parasite Balantidium coli is the largest known microbe pathogenic to humans, reaching sizes of up to 70 micrometers (which is enormous compared to body cells and other similar gut pathogens).
- A fertilized human egg cell (and for that matter an unfertilized one) is 0.12 mm in diameter — visible to the naked eye.
- Slime Molds. They are often comprised of a single cell, yet have the potential to grow as big as a dinner plate.
- Eggs, in general, are these. The yellow part is the cell itself. An ostrich's egg is the largest single cell known to man.
- Some astrobiologists speculate that there could be life on Titan, thanks to its being rich in hydrocarbons, as well as water. If that's true, it's believed that those lifeforms would take the form of microbes similar to bacteria and/or archaea found on Earth...only huge (maybe the size of a sheet of typical printer paper), perhaps to take advantage of limited sunlight for photosynthesis, or simply to out-compete other organisms.
- Thiomargarita magnifica is a bacterium found in mangrove swamps with an average length of 10mm and can reach sizes of 20mm, making it the largest bacterium in the world.