Bone Wraith

An ancient story tells of a mysterious being that walks the streets during the night. The only sounds it makes are feint clattering of bones, and a dry wheezing breath. Shrouded in darkness, it clambers to peoples houses unexpectedly, and enters them with ease. The being observes the occupants one by one, looming silently over their beds while they rest. It is patiently waiting, looking for the perfect target.
Once it has chosen a victim, the wraith reveals it's ragged boney arm and lowers onto the persons chest. At this point it is already to late, they cannot wake, they cannot move, they are hopelessly trapped by the wraith's force. Slowly it pushes it's boney fingers into flesh, grasping firmly it's victims ribcage. Then with a sudden movement it rips out every single bone, leaving it's victim alive, but just a fleshy mass incapable of movement.
Once it has acquired the skeleton, the wraith tucks it under it's torn cloak to add the bones to it's collection. No one knows what they are for. Perhaps to construct more wraiths to terrorize citizens, or to build upon itself to become more deadly. All that is known about them is they are nearly silent, evasive, deadly, and ruthless.