Pouring down like egg chow mein
All that's foul, all that's stained
Breeding in my toxic brain
You can smell it from a mile away.
A big, horrific pile of glop. Perhaps it's made of toxic sludge from a Corrupt Corporate Executive's industrial plant, or perhaps it's merely a colossal pile of dung.
But it's alive.
The Muck Monster is a living embodiment of filth and slop, and the Green Aesop tends to be his stomping grounds. Nothing tends to hammer an anti-pollution message home like an colossal, animate pile of (sometimes literal) crap. Plants die from this beastie's approach; sometimes animals and even people bite the dust from being in mere proximity to this abomination.
Compare Blob Monster, which is more transparent and tends to keep itself in one defined and consistent mass rather than constantly oozing and leaving parts of itself in its wake, (and is generally less smelly), and Talking Poo. See also Toxic Waste Can Do Anything, where the toxin creates a monster without being sentient itself.
A variant of the trope overlaps with Swamp Monster, creating a creature of living vegetation and/or mud (usually emphasizing the vegetation); this variant is often called a muck monster, but lacks the typical association with pollution and toxicity. They instead tend to have physical powers based on their inhuman bodily composition, such as Super Strength, Super Toughness and a Healing Factor, elemental plant-manipulating powers, or both.
- The Zingy animated icon used by British energy company EDF has often been likened, unfavourably, to a parasitical turd-monster. Embittered website Ad Turds has not been slow in likening it to South Park's Mr Hankey in its relentlessly cheerful disposition while - well, remaining a turd. The advertising agency has responded by making its colour a more orange-yellow rather than brown: but the current advertising depicting a very-large Zingy in the form of a hot-air balloon does make it look like a giant turd floating above British suburbia.
- Ginta uses Babbo: Alice to dispel this curse off "Gramps" in episode 97 of MÄR.
- Spirited Away has the Stink God, who is literally just a moving pile of sludge with eyes. His smell is so bad that it makes everyone's eyes water and makes all of the food around him rot. He turns out to actually be a River Spirit, and his filthy state was due to pollution in the river he inhabits.
- Tara Infirma, one of the minor characters in All-Ghouls School.
- Batman's enemy Clayface (all eight of them) fit the Trope in some way, although some are more humanoid than others. The worst part is, all of them were once human, except for the fifth one, who is a child of Clayface III and Clayface IV born AFTER they each gained their powers.
- The Heap is formed from the decaying vegetation of the swamp, wrapped around Baron Eric Von Emmelman's skeleton, and motivated by his indomitable will to live. Being made of animate vegetation makes the Heap extremely strong and resistant to physical damage. It also feeds by siphoning blood from living creatures, and can drain it with its touch.
- Sludge from The Ultraverse. Frank Hoag was a Dirty Cop who was killed and covered in chemicals by an explosion before his body was dumped in a sewer. The chemicals had regenerative properties and tried to heal Hoag, but combined the sewer substances with his body, transforming him into a huge mass of living slime.
- Weird Worlds: Garbage Man was originally an attorney named Richard Morse. Noticing something wrong with the Titan Pharmaceuticals account, he started investigating, but was betrayed by his Bad Boss to Titan. Morse was captured, drugged and experimented on by Mad Scientist Dr. Clive. Deciding the experiment was failure, Clive blew up the lab with all personnel still inside to destroy the evidence and silence any potential witnesses. However, Morse did not die. A chemical reaction from the drugs Clive had injected him with and the chemicals in the swamp around him transformed him into an inhuman pile of mobile garbage.
- Swamp Thing is a Spiritual Successor to The Heap, being a human scientist transformed into a sapient mass of moss, algae, roots and mud after an explosion in his lab soaked him in burning chemicals before he plunged into a nearby swamp in an attempt to extinguish the flames. This triggered a reaction that transformed him into a creature made of the slimy substance of the swamp. This was until the 80s, when Alan Moore instead retconned the Swamp Thing into purely a Plant Person, and the Elemental Embodiment of the plant kingdom at that; Swamp Thing had merely absorbed the memories of the human scientist who died, which was part of a ritual needed to spawn such an elemental as himself.
- Man-Thing is very similar to the original depiction of Swamp Thing; a scientist working on a Super Serum injects his prototype formula into himself whilst trying to escape from some thugs, only to be shot and crash into a swamp. The formula, combined with mystic energies bound up in the swamp itself, transformed the scientist into a nonsapient mass of plant-matter and mud. One aspect of Man-Thing's that is closer to the conventional Muck Monster is that it has the ability to secrete a highly corrosive, possibly incendiary acid as a weapon in combat.
- FernGully: The Last Rainforest: Hexxus, the Tim Curry-voiced pollution-demon villain, although he was the primordial spirit of destruction before he latched on to human inventions. His forms varied from a sludge-based blob monster to an exhaust fume-based ghost to a giant burning angel skeleton made of tar.
- Creepshow 2 had a large, flat monster resembling an oil slick, that dissolved any flesh it touched, inhabiting a lake.
- Dogma had a demon, the Golgothum, constructed from crap - specifically, the crap of all the prisoners crucified at Golgotha (yes, including Him). He's defeated by deodorant (which "knocks out strong odors").
- Godzilla vs. The Smog Monster, villain Hedorah has to be the most famous example of this trope, and it shows why one must never let alien organisms from a nebula where chemicals that are pollutants on Earth are its food arrive on Earth, lest it grow into a giant tadpole sludge demon that can drop lethal acid as it flies. Hedorah comes with a Meaningful Name with a dash of Exactly What It Says on the Tin as the name is derived from hedoro which is Japanese for "Sludge". In all of its forms, Hedorah is comprised primarily of the mineral substance Hedrium, which is also the source of its incredible strength, amorphous body and nigh-unstoppable abilities, including his Hedrium Ray, capable of burning Godzilla's flesh, and his ability to generate vast quantities of chemical ooze without it visibly affecting his size, even using it in an attempt to drown Godzilla at one point in the final battle. It took a combination of the JSDF using gigantic electrodes and Godzilla powering them with his Atomic Breath to finally bring Hedorah down for good.
- Mon Sturd. It's like Jack Frost (1997), except the Serial Killer was genetically fused with shit instead of snow.
- The H-Man is an earlier iteration of this, but explicitly radioactive (hence the name). It Was Once a Man, and now must eat other humans in order to retain its shape.
- Armageddon from The Return of Hanuman is a monster formed from a volcano, mostly because of the many inorganic trash contained inside and activated when Rahu and Ketu's staff went inside of the volcano.
- The low-budget 1986 horror film Spookies had Muck Men, who made explosive flatulence sounds when they came to get you (which presumably caused a bit of confusion among viewers as to whether they were muck monsters or poo monsters).
- Visser Three from Animorphs is a shapeshifter with two forms like this, seen in The Weakness and The Hidden respectively.
- The deities Abhoth and Ubbo-Sathla in Clark Ashton Smith's Cthulhu Mythos stories.
- The 1940 short story "It!" by Theodore Sturgeon is about a plant monster that is ultimately revealed to have formed around a human skeleton in a swamp. The story is generally regarded as having been the inspiration for The Heap, Man-Thing and Swamp Thing.
- During the lifeforce crisis in Reaper Man, one of the Unseen University's compost heaps comes to life. It attacks the gardener and dissolves its way through the main door before the wizards blew it up with a bottle of Wow-Wow sauce.
- In The Royal Book of Oz, the first Oz story by Ruth Plumly Thompson, the Scarecrow briefly encounters Middlings, man-like creatures made of mud.
- The title creature in Slime by William Essex: a living lake of toxic waste that eats people and animals.
- Eva Mudlark of The Aquabats! Super Show! has made several of these out of anger from being treated as a lowly garbage collector.
- Doctor Who: In "Gridlock", the Macra live at the bottom of the Motorway and feed on the gas fumes created by the huge numbers of Flying Cars stuck in the universe's worst traffic jam.
- Monster Warriors: In "Revenge Of The Mud Maniac", a giant mud monster is on the attack in Capital City.
- Call of Cthulhu had a version of Clark Ashton Smith's Abhoth (see above).
- Dungeons & Dragons has a number of these, such as the grey ooze and the demon prince Juiblex.
- A swamp that's tainted by magical pollution can create mudmen, which are Exactly What It Says on the Tin. Not very intelligent, they try to drown anything that enters their swamp out of an instinctual urge, often destroying themselves in kamikaze attacks as they try to smother their foes.
- Forgotten Realms: Moander, a minor evil god, manifests in the form of a gargantuan crawling heap of rotting vegetation.
- Ravenloft: The Darklord Malus Scleris rules a domain that is the horror of unlimited pollution made real, and it is filled with these kind of monsters. Scleris is a pre-industrial version of a Corrupt Corporate Executive; his Freudian Excuse is that his father, a druid, only cared about his work, not about his son, so in return he hates Nature for taking his father away from him. His MO is control of horrible and disgusting diseases.
- Pathfinder has the Kaiju Vorgozen, a huge acidic sludge monster created by magical experimentation Gone Horribly Wrong (or possibly Gone Horribly Right— the aftermath of Vorgozen's creation left few clues as to the original intent of the wizards responsible). She warps magic in a wide area around her, and can "infuse" herself into the terrain to travel quickly or escape in the unlikely event she finds herself threatened.
- Shadowrun: City spirits usually manifest as piles of ordinary litter, unsightly but not all that icky. Toxic nature spirits manifest as contaminated water, smog, or really foul rubbish.
- The Binding of Isaac has a lot of poo-themed enemies, including Dips, Squirts and Dingas (each progressively larger and which split into their smaller kin when killed), and bosses Dingle, Dangle, the Turdlings and Brownie.
- Bulb Boy has a Puzzle Boss based on this concept. After the protagonist eats the cooked corpse of an evil zombie chicken the resulting bowel movement creates a large worm-like turd monster that must be flushed down the toilet before it eats Bulb Boy.
- City of Villains: The Slag Golems enemy group are terrifying monstrosities of living cast-off metal, shambling figures composed of crudely sentient dross and detritus, eager to pound anyone who crosses them into compost for the island.
- One of the bosses from Conker's Bad Fur Day was the Great Mighty Poo.
- Demon's Crest on the SNES has the boss "Crawler," a huge mass of melted-looking flesh that takes on a semi-humanoid form after it swallows some bones. It can spawn zombie-like creatures from its body.
- Digimon has Raremon, a crawling, blubbery pile of rotten flesh entangled with random cybernetics. It smells like dead fish and vomits as an attack. Raremon is one of several "garbage" type Digimon, monster who basically failed their evolution. Others include Sukamon, a living pile of feces, the slug-like Numemon, and Garbagemon, which even lives in a trash can.
- Dragon's Lair has mudmen, which unlike the other monsters cannot be killed, only avoided.
- EarthBound: Master Belch and his upgraded form, Master Barf. There are also the smaller monsters like "Pile of Puke" and "Stink Spirit".
- Pikmin: The Smoky Progg is a horrifying crawling cloud of pollution that instantly kills any Pikmin it touches. Not even unpicked ones are safe from its wrath.
- Pokémon: This is a recurring archetype for Poison-type Pokémon:
- Pokémon Red and Blue has two Muck Monsters in Grimer and its evolved form, Muk. In the Pokémon anime, Ash's Muk was (initially) so smelly that it stank even after it had been captured in a Poké Ball. When he teleported it to Professor Oak's, it proceeded to engulf half the lab and reduced Professor Oak to ranting. Of course, said Muk really just wants a hug.
- Koffing and Weezing are based on pollution, but they're more inspired by smog than slime, although they do possess the ability to spit globs of slime.
- Pokémon Black and White has the garbage Pokémon Trubbish and Garbodor. Their bodies pick up trash as they go, so they're ironically useful in keeping places clean.
- The Amoeboids in the Ratchet & Clank series are a kind of slime monster that walks in circles and says "Nein!". When hit, they split into two, half as small slime monsters (except for the smallest sort, which just disappears). The biggest ones will split five times, meaning that you have to kill sixty-three slimes in total.
- Shantae: The Mud Bog areas are filled with Mud Bog creatures made out of the stinky, sludgy mess that the area is filled with. They either jump around in a blobby mass or pop out of the swampy floors and ceilings.
- The Tarr in Slime Rancher are this, being ravenous blob monsters born from when a largo slime eats a plort that it normally doesn't make. They probably have some kind of oil in them to make that rainbow sheen on their surface. Luckily for ranchers and slimes alike, Tarr are easily killed with a splash or two of fresh water.
- Wild ARMs 2 had the boss "Drawdo," which resembled several dead fish melded together and attacked with every status effect in the game.
- Aladdin: The Series: In several episodes, the heroes ran afoul of the Al-Muddies, elemental spirits which are made of living mud, live underground, and are carnivores known to prey on humans. Normal ones are feral, dimwitted, and brutish creatures who tend to attack in mobs; their Sultan, however, stands out because of his titanic size and his incredible cunning and intelligence (not to mention being able to talk), and a fondness for cooking victims. (Even going so far as to call himself "a gourmet".)
- Atomic Puppet: Mudman is a minor member of the Rogues Gallery able to possess other beings, shapeshift, and regenerate From a Single Cell.
- Captain Planet has an episode with one of these. In this case it's an artificial organism that was supposed to eat garbage, but of course when Sly Sludge used it, it went horribly wrong and turned into a Grey Goo that threatened to turn the entire planet into one big pile of living garbage.
- Goof Troop: One episode features a Corrupt Corporate Executive who had become a Muck Monster due to overexposure to all the pollution created by his factory. Goofy returns him back to normal with a jar full of fresh air.
- Lilo & Stitch: The Series: Experiment 505, Ploot, is designed to collect and absorb pollution and turn it into a toxic sludge to flood cities with. The more he collects, the bigger and grimier he gets.
- The New Adventures of Winnie the Pooh: In "Cleanliness Is Next to Impossible", Crud is a creature made from the filth under Christopher Robin's bed. A bar of soap acts like kryptonite to him and he is defeated by being sucked into a vacuum cleaner.
- The Owl House: Abominations are large, purple sludge monsters that serve as muscle for those who summon them. More skilled summoners can also use them as a Morph Weapon.
- Samurai Jack: A group of mud people come to offer Aku a tribute for being allowed to live on Earth (an equally muddy statue of Aku). All Aku really cares about is that they are dripping mud all over his floor.
Aku: I just had it vacuumed! Out! Out!
- Teenage Mutant Ninja Turtles (1987): On several occasions the mutagen spawns these creatures; they have names like "mud monsters" and "Mutagen Man". Basically, the theory is that this is what happens when the mutagen produces something that doesn't have the dignity of resembling a particular animal like a turtle. (And of course, the accidental workings of a mutaagen in Real Life are much more likely to produce a monstrosity like this than an anthropomorphic turtle....)
- ThunderCats (1985): In "Mandora: The Evil Chaser", one of villains is a Muck Monster known as The Living Ooze. Defeated with a powerful weapon of the ancients — soap.
- The Tick:
- The Filth is a slimy sewer-dwelling creatures with, erm, tapered heads.
- A variation with a snot-based clone of the Tick himself created by the being from the alternate dimension down the hall. Not exactly a blob of muck, but it was made of snot/mucus and, while shaped like the tick, could squish itself into other shapes and use it's semi-gelatinous consistency to seep through cracks and around attacks and such.
- Most of the foul-smelling slime found in stagnant ponds, along the tide line of beaches, and other messy natural settings is made up of mats of living bacteria by the quadrillions. They don't walk en masse, but individual bacteria do move around within their filmy habitats.