YHWH is a powerful god-like figure in Angel Sanctuary.
A being from somewhere else. He has no real physical form, but resides in Etamenanki in the form of a giant computer-robot. The entire universe was created just to test an equation that he had fashioned, and he cares nothing for the suffering and injustice endured by humans and angels alike.
He created Adam Kadmon in order for Adam Kadmon to "step-in" whenever he (God) was "sleeping" and after Adam Kadmon rebelled on him out of love for his children he splits Adam Kadmon's powers into Alexiel and Rociel and used his head to bread new angels and made use of Alexiel and Rociel later on he used his new creations to kill the Angels, Demons and Humans then Setsuna Mudo came and confronted him.
In the end he is defeated by Setsuna with the help of Lucifer. Whether or not he was "killed" is never revealed, but since the universe did not cease to exist upon his defeat, it is clear that the unconscious mind of YHWH is still functioning.