Fleshgait

Fleshgait is a general term for a creature that appears to be humanoid, but upon closer inspection something about them isn't quite right.

Their origins are mysterious, and the theories about what exactly they are and what they're capable of are varied.

Some think these are humanoids who have fed on the flesh of their own, becoming cursed by the Gods for indulging in such a forbidden act - even if it was necessary for survival reasons. They become monsters, longing for flesh and unable to stop until they are inevitably killed.

Others argue they are mages who dove too far into certain subjects (what subject that may be varies as much as anything else) and ended up cursed as a result, either by a God or by the knowledge itself. They wander in search of more, devouring victims to absorb their memories in hopes of finding a way to break their curse.

Whatever they are, at least a few facts are known for certain; they are faster and stronger than most normal humanoids, they are smart enough to set traps, mimic voices, and lure individuals away from a group to hunt, and they absolutely hunt and kill humanoids.

Killing them doesn't appear to be difficult, but once again the methods vary from needing to stake them in the heart with specific types of wood that would have been important to various regions, to needing to burn the stake first so the embers can melt the creature's icy heart, to simple decapitation and so many more.

So far the above listed methods seem to work with some level of consistency, but actual results may vary.