Monstrous Humanoids are beings that look (somewhat) human, but definitely aren't.
It can be their original form, but they may also be the result of a monster that starts undergoing transformations that make it more human instead of yet more monstrous, or a human transforming into a monster but only going there halfway, or doing so much evil that they gradually become monsters. This trope is not defined by the nature of the creature but by its form.
Expect the more "human" of them to show their true monstrous features at some point. While Lovecraftian Superpowers can act as a qualification, they aren't a requirement, and be careful the example doesn't qualify for Humanoid Abomination instead, as Eldritch Abominations in human form rarely qualify for this trope. See Red Right Hand for examples of monstrous features being used to indicate evilness.
Uncanny Valley is related, but distinct from this trope, as monstrous humanoids, while human-looking, are still recognizably monstrous, while Uncanny Valley creeps people out because the creature looks almost indistinguishable from humans except for the one thing that is "off" about them.
Many mythological beings take this form - as a physical manifestation of intelligence and civilization in the human form and assorted forces of wilderness in the monster, the result being a supernatural Liminal Being. That this form is so common is partly due to Most Writers Are Human, as the monsters become more comprehensible and identifiable as advanced and cunning beings as their anthropomorphism increases, but ceasing it before they become too human and progressing into Uncanny Valley.
- All Trolls Are Different
- Beast Man
- Cute Monster Girl
- Draconic Humanoid
- Fauns and Satyrs
- Harping on About Harpies
- Horned Humanoid
- Our Ghouls Are Creepier (on those occasions where they're treated as a species in their own right rather than as a variety of undead)
- Our Goblins Are Different
- Our Ogres Are Hungrier
- Our Orcs Are Different
- Winged Humanoid
Compare and contrast Humanoid Abomination, where the creature is not a humanoid, but just humanoid.
- The Apostles of all used to be humans before offering up something they cherish the most - usually a loved one - to transform into man-eating, often-Lovecraftian abominations. Even in their human form, most have monstrous traits that give their true nature away, like Wyald's ape-like features; the Baron's fangs and yellow, snake-like eyes; and Zodd's red eyes, fangs, feline facial features, and pointed ears.
- Of the five members of the Godhand, Void has a skull-like face with a massive, protruding brain; Slan has four bat wings and tentacles for hair; and Femto has a beak-shaped "helmet" and cape-like wings - but aside from that they are mostly human in appearance..
- Bleach: After Aizen merges with the Hogyoku and undergoes four One-Winged Angel transformations, each more monstrous than the last until climaxing in a Hollow-like monster with three Milky White Eyes, six wings with Hollow masks and eyes with Hellish Pupils, three huge holes in his body. His facial skin splits apart to reveal a black skull, and his right hand is completely fused to his Zanpakuto.
- The titular warriors are a squad of women who were infused with the flesh and blood of monsters called Yoma, giving them similar abilities at the cost of risking becoming a monster themselves. This process bleaches their skin and hair, and turns their eyes silver, and the more power they draw on the more monstrous they become in appearance.
- The Yoma themselves qualify, being humans infected with a parasite that transforms them into flesh-eating humanoid monsters.
- There are so many examples from the Digimon franchise that to list them all would require its own page.
- Alucard from Hellsing. He was once a man, specifically Vlad III Tepes, aka Dracula, but over centuries of consuming people and being experimented on by the Hellsing Organization he acquired Lovecraftian Superpowers so far beyond what a normal vampire is capable of that he almost qualifies as a Humanoid Abomination. In his 'normal' form he's not quite human - you can't fit that many pointy teeth in a human mouth - and he almost always manifests his "true form" as an extension of his human form.
- Naraku was a mutilated thief named Onigumo before he assimilated countless demons into his body, gaining the ability to go from a Bishonen human form to a gigantic mass of tentacles, insectile legs, razor sharp diamonds, and spiritually poisonous acid-gas at will.
- Moryomaru is an artificial yokai created by Naraku's offshoot Hakudoshi, and later acts as a Lovecraftian bulletproof vest for Akago, Naraku's telepathic Fetus Terrible Soul Jar. He eventually becomes powerful enough to take on Naraku, and is eaten from the inside out.
- The "Fractured Humans" from Jagaaaaaan are a prime example as their monstrous appearances is Body Horror galore, as they morph their bodies to mirror their suppressed urges, warping their heads and forms beyond reasoning as they manifest, making every case unique as it manifests.
- Orochimaru appears to be a tall, thin man with unnaturally pale skin and long black hair. However, as a result of attempting to acquire Snake Sage Mode he has Hellish Pupils, fangs, insane regenerative capabilities, and a variety of snake-themed powers. His true form, after years of self-experimentation, is a giant snake-like monstrosity composed of hundreds of smaller snakes, and he can take over other peoples' bodies and use them as his own until his power burns them out.
- Kabuto Yakushi, Orochimaru's right-hand man, becomes one after he infuses himself with Orochimaru's, Juugo's, Suigetsu's, Karin's, and the Sound Four's DNA, gaining Hellish Pupils, scales all over his body, all of Orochimaru's and the others' powers, a massive snake where his navel used to be, and can use Snake Sage Mode to turn himself into a humanoid dragon of sorts.
- Any of the Jinchuriki, by virtue of having Tailed Beasts sealed inside them. When they get suffciently upset or angry the Tailed Beast they house starts to try to take over, in stages varying from a simple power up, a Battle Aura (with a mind of its own), and becoming a feral miniture of the Beast, until finally the Beast breaks free and rampages once more. Each new level starts doing more and more damage to the Jinchuriki though Killer B and later Naruto are able to use these states without dying/losing control
- In Spirited Away, the staff and guests of Yubaba's bathhouse are Youkai of various degrees of anthropomorphism, though they're all there to work or relax just as would be expected in any human tourist trap.
- The aliens (and thus Concrete himself) in Concrete are as humanoid as a gingerbread man, and just as featureless. Not really scary on the page, but remember they're around 8 feet tall, covered in a stony skin, disproportionately strong, and weigh in at over half a ton each, and you realize how horrible they must be to be around in-universe, especially when the vaguely humanoid things are moving around, looking at you, or twisting their featureless faces into facsimiles of human expressions as Concrete always does. The monstrous aspect really kicks in when you think about their size and humanoid form in comparison to a human, though it's further offset on the page by their faces being not unlike now commonplace emojis.
- Red Robin: What exactly the Council of Spiders member code-named Goliath really is was never addressed but he's a very tall humanoid figure covered in fur with an extra set of eyes, an extra set of arms and Monstrous Mandibles.
- Spawn: Hellspawn, titular character included, are undead humans reanimated with necroplasm and bonded to a demonic symbiote, and possess a wide range of powers ranging from shapeshifting to limited reality warping.
- Whenever Spider-Man's "Spider" part overtakes over the "Man" part he transforms into a feral arachnoid monstrosity, as seen during the "Man-Spider" and The Other arcs. His clone Kaine underwent a similar metamorphosis a la The Other after being killed by the Lobos siblings.
- Venom, Carnage, and the other symbiotes can turn their hosts into creatures with More Teeth than the Osmond Family, Absurdly Sharp Claws, Overly Long Tongues, and Lovecraftian Superpowers.
- Doomsday was a Kryptonian genetically modified as a fetus to become an eternally resurrecting, constantly mutating monster. He wiped out all the other monsters on Krypton and was sealed away, eventually making his way to earth... where he killed Superman.
- The Pale Man from Pan's Labyrinth is a pale, skeletal, humanoid creature with eyes on the palms of its hands that usually sits at the head of a table laden with an enchanted feast. Anyone who eats the food wakes him up and, well...
- The Immortals in 300 are visualized as some undefined race of humanoid monsters with killer teeth fighting for dark emperor Xerxes. They seem human at first because they're all wearing ominous masks, but when one of them has his mask blown off, the Spartan who did so shows visible dread when he sees that his opponent isn't even human.
- The Night Flier: Far from a handsome gentleman, the vampire Dwight Renfield will always appear as a barely-human bat-like monster to his victims.
- The Parshendi in The Stormlight Archive are of roughly human shape in their base forms, at any rate and can in fact speak Alethi (the language of the protagonists). However, they have red-and-black marbled skin, mysterious telepathic powers, and are actually limited shapeshifters. They can assume a number of different forms to suit the task at hand. The five known so far are warform (causes them to grow armor plate and become physically strong), workform (much like warform, but without the armor and with a block against violence), mateform (in which they are fertile and obsessed with sex), nimbleform(dexterous and careful), and dullform (their baseline form, has no special features or powers). They also may be able to turn into this world's version of demons. They also are noted for killing King Gavilar of Alethekar on the same night they signed a peace treaty with him, for no reason anyone's been able to figure out.
- The Iron Teeth web serial’s forests are haunted by many different types of dangerous monsters. There are a bunch of guys in this story who do look human, more or less. For example ghouls and hobgoblins.
- Trollocs from The Wheel of Time are bulky humanoids with a variety of bestial features mixed in (individual trollocs might have goat, wolf, eagle or some twisted combination thereof, and as such are wildly diverse, but always monstrous). They're magically-engineered footsoldiers for the Shadow, and have high aggression but subhuman intelligence. Their more intelligent and humanlike cousins/offshoots, the myrddraal, fall more into Uncanny Valley with a dash of Humanoid Abomination, though they share some of the trollocs' bestial habits, including cannibalism.
- J. R. R. Tolkien 's books:
- Orcs and goblins were originally elves who were corrupted and mutated by Melkor into warlike, predatory creatures skilled at metalwork and engineering.
- Trolls were created by Melkor as a parody of the Ents, being massive, unintelligent creatures that usually turn to stone in the sunlight.
- Gollum was once a Stoor hobbit named Sméagol, who lived in a community on the banks of the Anduin River. After coming into possession of the One Ring, over the course of 500 years he was twisted into a pale, emaciated creature with fangs and glowing eyes, capable of clinging to sheer surfaces like a spider.
- In Brennus this is known as the Chimaera trait, an expression of the Physique power. It normally ranges from minor traits to still-humanoid full-body makeovers, but extreme cases can be outright weird or abstract.
- Eclipse really enjoys coming up with distinctly... well, inhuman humanoids. Most notably, we have Nyurei Arihiku, who has jet-black skin with a red outline that flares up whenever angry or excited, along with an elongated skull, skin-less lips, an Eyeless Face, and an ability to devour Hellhounds via absorption.
- The Traitor Son Cycle has Orley's warband, who used to be humans before they became giant and misshapen, grew horns and had their skin covered in some oily, icky substance that acts as an extra protection.
- The creature that Molly encounters in the bank in The Taking is a Humanoid Abomination, but has enough typically "monstrous" features such as bulging red eyes and huge claws to overlap solidly into this as well.
- Some of the monsters in Supernatural fall into this category including ghosts, zombies, golems, rawheads, and wendigo.
- The monster from the Upside Down in Stranger Things definitely qualifies — too tall and gauntly muscled to be human, with disturbingly long arms and hands, a mouth like a five-petalled carnivorous flower, and More Teeth than the Osmond Family.
- The antagonist of Varkon, who has small fangs and a rounded, brutish face filled with wrinkles.
- An actual creature type in Dungeons & Dragons, differentiated from normal humanoids by their monstrous or animalistic features. Examples include minotaurs, hags, centaurs, and yuan-ti.
- Nightmare, the Big Bad of the Soul Series, starts off as the Super-Powered Evil Side of Soul Edge's protagonist Siegfried Schtauffen in SoulCalibur I and II, but later becomes a suit of Animated Armor in III and IV before gaining a new host in V. His defining characteristics are a blue suit of armour, glowing red eyes, a grotesquely mutated right hand, and a living BFS called Soul Edge.
- Sephiroth, the Big Bad of Final Fantasy VII, was infused with Jenova cells while a fetus. He has long white hair, glowing green eyes with Hellish Pupils, and is touted as the strongest Soldier First Class in existence. He later merges with Jenova, graduating to a full-blown Humanoid Abomination.
- Alex Mercer, James Heller, and the Evolved from the [PROTOTYPE] series are the avatars of a viral bioweapon called the BLACKLIGHT Virus, which grants them an array of Lovecraftian Superpowers. Elizabeth Greene, the Big Bad of the first game, is a Humanoid Abomination who is the avatar for the beta version of the BLACKLIGHT Virus, REDLIGHT.
- In Skyrim's Dawnguard DLC, Lord Harkon is featured as a seemingly ordinary man with unnerving eyes, but has the ability to turn into a humanoid bat-like monstrosity.
- Dark Samus, the main antagonist of the Metroid Prime Trilogy, resembles a black, biomechanical version of Samus Aran. "She" began as the titular Metroid Prime, a Metroid mutated by prolonged exposure to Phazon and prophesied by the Chozo as the Worm. Following its defeat at the hands of Samus, it merged with her Phazon Suit and came back as a twisted doppelganger bent on spreading Phazon throughout the universe and even other dimensions.
- The vast majority of Pokémon in the "Human-Like" Egg Group.
- The J'avo from Resident Evil 6 look and behave human enough to pass as one. At least until they lose their mask or bandanas and you see that they have eyes where there shouldn't be eyes. It gets even worse when they lose a limb and insect parts erupt from their bodies to replace them.
- And if they burst into flames and spin a cocoon, well, run.
- SCP Foundation
- SCP-974 ("Treehouse Predator"). SCP-974 is a meat-eating creature that looks like a young human child. It prefers to kill and eat prepubescent children (ages 6-12 years old).
- SCP-1293 ("Squeedle Deedle Dee!"). They look like human beings wearing costumes, but the costumes are actually part of their bodies. The female versions bear their young live through their mouths, and the young are born fully mature in intelligence and size.
- The Rake is a wiry human figure, pale and hairless with cavernous eyes. It is often depicted as an unnaturally vicious predator, whether of human intelligence or animal cunning; however, it is also related to the mara of folklore, as it is described as slipping into bedrooms at night and watching the sleepers or leaving inexplicable slashes on their arms.
- The Creepypasta story "Genetic Memory" is based around the idea that there are a group of characteristics (namely elongated, pale faces, sunken eyes, and sharp teeth) that seem to inspire an instinctive fear in humanity all across the world. In this illustrated version a man out in the cold with a covered face comes up to another and talks about all this, and comparing it to Primal Fears that are similarly widespread, like fear of the dark and such. He ponders what could inspire such fear... and then he removes his scarf, snow goggles, and hat to show the other man exactly what scared ancient humans so much.
- RWBY: From the back, Salem looks like a human woman with white hair that is worn in a bun. However, her skin is a ghastly white covered in reddish veins that are visible on her arms and face. Her eyes are black pits where the sclera should be, with glowing red irises and pupils that are vertically slit like a domestic cat's. Her appearance and colour scheme are shared with the Monsters of Grimm, but it's not clear whether she's a humanoid Grimm or was once a human that has been dehumanised via infection or possession by a Grimm.
- Marceline from Adventure Time is a vampiress who can transform into a variety of Eldritch Abomination-esque forms at will, usually for the sake of tormenting Finn and Jake. It's also worth noting that her father, Hunson Abadeer, is a blue-skinned soul-sucking humanoid demon with similar powers, which stem from the Nightosphere Amulet.
- Grendel in Beowulf, he is depicted as a misshapen humanoid that is tall and lean and parts of him are inside out.