The original is named Mar'Ament, which is a name I made up on the assumption that it sounded elven and meant armement(See what I did there?). Two nicknames include "The Formless One", and "The Black Blood".
Still trying to flesh it out a bit, but for now is is a sympiote, or a parasyte if you want, in an elvan female host, much to his distaste for now. He can't be killed, even with the death of a host, but can be sealed away, usually in a magical container of some sort. He has no defined form for himself, hence the first title, but can form into anything from and aminal or humanoid shape, to a weapon or armor stronger than steel.
I would describe more, but its a pain in the rear typing on a nook.