Sosuke Aizen, post merging with the Hogyoku. He undergoes four One-Winged Angel transformations, each more monstrous than the last, culminating as a Hollow-like monster with three Milky White Eyes, six wings with Hollow masks and eyes with horizontally slitted pupils, three huge holes in his body, facial skin splitting apart to reveal a black skull, and his right hand completely fused to his Zanpakuto.
Vasto Lorde-class Menos and Arrancar qualify; the former being immensely powerful Hollows that have assumed a humanoid form after devouring thousands, if not millions, of other Hollows; and the latter being Hollows that have broken their White Mask of Doom to attain a humanoid form and Soul Reaper-like powers.
Alucard from Hellsing. He was once a man, specifically Vlad III Tepes, aka Dracula, but over centuries of consuming people he acquired Lovecraftian Superpowers so far beyond what a normal vampire is capable of that he almost qualifies for 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.
The Yoma themselves qualify, being humans infected with a parasite that transforms them into flesh-eating humanoid monsters.
The Apostles of Berserk 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. The Godhand take that process a step further.
Orochimaru appears to be a tall, thin man with long black hair. However, he also 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 righthand 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 the ability to turn himself into a humanoid dragon of sorts.
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.
There are so many examples from the Digimon franchise that to list them all would require its own page.
[[folder: Comic Books]]
Hellspawn in the Spawn comics, 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.
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.
The vast majority of Pokémon in the "Human-Like" Egg Group.
[[folder: Web Original]]
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.
[[folder: Western Animation]]
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.
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.
Is that what you meant to do?
You are saying this draft has a ready-to-publish hat it does not deserve and you are taking it back.