Penanggalan Picture

"The first of her kind was an old woman. One day, while performing her religious duty, she was startled by a strange man and accidentally kicked her own head off. That head and her organs flew away to a treetop and became a demon."
"That might be the stupidest thing I've ever heard. No offense."
- Mike Mignola, Hellboy

What if the mythic Penanggalan was realized in the form of an infectious, bodyjacking extrasolar parasite that liquefies the flesh and bones and swells the internal organs with electrolytically produced hydrogen, turning the unfortunate victim into a necrotic parody of a Barlowe floater? Many of the organ systems continue to function, albeit not in their original fashion, and the infectious organism even retains portions of the brain intact to enable basic motor functions and environmental sensitivity. Part floating photosynthetic fungus, part reflexive opportunistic predator, the macabre spectre would certainly be held in superstitious dread by the primitive societies of an isolated Post-Collapse colony world. Some variant of this same pseudoscientific monster generation template, applied to hapless human or quasi-human hosts, could produce extrasolar "Naga," "Gorgons," and other such mythological nightmares, methinks.

Or maybe she just came down with a bad case of Flying Polyps.