Vargouille

Vargouilles are floating Neutral Evil heads with bat wings and small floppy tentacles. Their origin is "Tarterus" so those "deepest pits of the lower planes" (not necessarily Carceri although, yeah, they're there), and areas where such planes are meddled-with, are the most likely places to find them. Luckily they are blind in natural sunlight and they dislike light generally. (Or so it went in First/Second Edition AD&D, starting second Monster Manual.)

Their bite is venomous, such that - failing the saving-throw - those 1d4 hitpoints are lost forever, excepting a wish. Again: so first-edition went.

Second Edition left the concept alone until the first Planescape Monstrous Compendium Appendix. This nerfed the poison but added other horrendous abilities to compensate. First, a shriek effect: to paralyze nonvargouilles within earshot and eyeshot, making the kissykissy easier. The most-feared attack (and mode of reproduction) is to kiss you on the lips (muah!), clearly easier if you already can't move. This, failing a saving-throw, passes on a disease: over time, your head takes on vargouille traits until, at the end, the body is shunted aside and the head floats away. So almost a different animal altogether, but a greatly improved one.

Third-Edition, raising this thing to the mainline Monster Manual, further omitted the disabilities in sunlight. Frankly that was dumb. At least they imposed a sensible 60-foot range on the shriek and didn't demand line-of-sight.

The vargouille might seem to gargoyles as jermlaine to gremlins: some Frenchified way around a public-domain term such as to make it not public. In this case the source-material attempted more creativity. And it's under the OGL anyway so D&D and Pathfinder parties can enjoy this old-school monster together.

Monte Cook seems inordinately fond of this beastie. The Vargouille Knife is a bane in the Banewarrens of Ptolus; if you hit someone with it, his/her head turns into this. Also there's a plane in Beyond Countless Doorways where vargouilles flit around swapping bodies.

As to where they came from: the MC Appendix proposes, but doesn't insist, that some (mortal) mage Rozvankee the Strategist created them in a feudal realm somewhere up here. Then she became a lich and retired to the Abyss, making her way as a pirate with a large flock of these monsters. Thus allowing for vargouilles' reproduction-ability on the Prime Plane.

The vargouille also has an elite version called the shrieking terror. The shrieking terror looks like a winged starfish with human heads on the ends of each arm. They can also turn people to vargouilles with their kiss. The origin of the shrieking terror is unknown but it is suspected to be the result of somebody combining the traits of a vargouille with a hydra. How a vargouille reacts to meeting with a shrieking terror varies. Some will see it an abomination and will immediately attack it in a swarm, while others will hold the shrieking terror in awe and will fight other vargouilles to protect it.