There is no end to the mayhem in Michael Jackson's mini movie Ghosts. Michael (as "The Maestro") pulls a few funny faces and then pulls his face off as if it were a mask. Later on he pulls his entire skin off and does a song and dance number as a skeleton, and then he turns into a ghoul. He turns into water and possesses the mayor (by having the mayor drink him - um, Squick). Then his arm bursts out of the mayor's chest and causes the mayor to turn into a ghoul. He turns back to normal (for Michael) and crumbles into dust - then he appears as a giant ghoul face which scares the "Mayor" into leaping to his doom.
The Jackson 5's Torture. Early on, one of the brothers accidentally pushes his hand into a giant eyeball, getting his hand stuck in eye goo. He pulls it out, only to discover there's an eyeball in his palm.
Al has claimed he became a vegan because he's terrified of being morbidly obese after doing that video.
The full version of the "Rock DJ" music video by Robbie Williams, which involves Robbie stripping to get the attention of a female DJ. When he gets down to bare skin, he decides that isn't enough, so he begins to peel all of his flesh off, layer by layer, until he's left as an animated dancing skeleton. Naturally, this gets the DJ's attention.
The video for "Rubber Johnny" by Aphex Twin is this trope distilled to its essence. It's all from a night vision camera viewpoint as these unseen characters watch as this freakish, vaguely human thing with bulbous eyes and a twitchy disposition slowly goes from content to a body spasmy berserk rage, interspersed with scenes of a dog that happens to share the same traits. And that's only the beginning — I love it.
Daft Punk gives us "The Prime Time Of Your Life". A young woman in a world, judging by her photographs, inhabited by skeletons decides to become one...using a razor. Once she gets her skin off, she dies. Her parents rush in, and the camera pans over the pictures again - everyone's normal. She was anorexic.
The Music video for MGMT's Flash Delirum for those who havent seen it, it involves two guys coming back home, one has a bandage over a wound, halfway through the video he removes the bandage to reveal a singing slit in his throat, a guy reaches down into his throat and pulls out a long,disgusting fish, it's something you don't want to watch while eating.
The end of Tom Petty's "Don't Come Around Here No More" certainly qualifies. Biggest problem, other than the cannibalism itself, is that she's still very much awake and attempting to squirm even as the knife goes in....
The Talking Heads' "Seen and Not Seen" is one of the subtlest examples of body horror on this list, especially since it is delivered in a near monotone. It tells the story of a man who tries to mold his own face into the ideal he sees in the media using the force of his own will. He imagines that other people have the same ability, and mold their faces to suit their personalities. But then he comes to wondering if some people might have chosen their ideal poorly, and arrived at a face completely different from them, or could be stuck in transition between two faces, neither of which they want. The song ends with David Byrne intoning, "He wonders if he too might have made a similar mistake."
The concept of Lou Reed's video for "No Money Down" involves an Uncanny Valley edition of Reed tearing off his own skin in a grotesque manner to reveal a robotic version of himself.
The lyrics imply, however, that the body horror is purely symbolic and not actually happening to anyone. The implications of this, however, make the body horror even more unsettling.
The song The Invasion From Within by Tsunami Bomb was all about this, via a Puppeteer Parasite. The song was used in the US release of the original Disgaea but had nothing to do with the plot.
Lemon Demon's CryptoSanta references the trope directly:
Body horror, tendons snapping / Ribbons and wrapping, stocking stuffing / Skin is sloughing, bones are bowing / Something is growing / Something. Ohhhh!
An early example of this in music is the English traditional song "Johnny I Hardly Knew Ye", first released in Originally a dark parody of "When Johnny Comes Marching Home", it is now known primarily as an anti-war song. The eponymous Johnny is a young soldier who comes home from Ceylon (Sri Lanka today), the song gradually detailing injuries he suffered from the war until the second-to-last stanza reveals him to be an "armless, boneless, chickenless egg".