I had an idea for a monster, although I don’t know if it’s original. I call it a “Gaunt” (although I’m sure that name has been applied to something else). It’s a sort of undead of someone who starved to death, or a walking skeleton still with the skin, hair and eyes.
How you get a gaunt is particularly horrifiying: An evil wizard or sorcerer locks someone in a cell and starves them. The only food they’re given is human flesh laced with magical additives- but not enough to stay alive, only enough to slow down how long it takes to starve to death. Except that they don’t quite ever die exactly, but aren’t really alive anymore either. They’ve passed out of the realm of human existence into something monstrous.
No one put through the full treatment can resist becoming a gaunt, except by truly dying. They have no more will, identity, or memory (although they can retain trace associations of their past life). They will obey the instructions of the evil magic user who is their master, but otherwise show little sentience. They can be “killed” by being physically destroyed- fire, hacked to shreds- but are unaffected by wounds, poison or disease. They are suprisingly strong for how skinny they are (up to max mechanical load limit of bone). They require live bloody flesh, preferably human, for energy. If deprived of it they will go dormant indefinitely but cannot perish from lack of food.
Gaunts are a way that evil magic users can reduce an enemy to a slave as a horrifying example to others. They’re usually expendable although creating more is a bothersome and time-consuming process. They’re used as assassins, to terrorize populations, and occasionally as puppets to perform tasks that only undead can do.