Hel

Hel is a former celestial deity and bride of Asherah. When the heavens and the planes were still young, she opposed the creation of beings with free will, believing that lesser beings would consume all of creation if not rigidly controlled. She delighted in the lush forests of the Feywild and the blinding beauty of Celestia. She would commonly stroll in the lands of the inner elemental planes in wonder. Hel despaired at the thought of what lesser thinking creatures could do to such beauty if allowed freedom. When her protestations fell on deaf ears, she rebelled against the heavens. She gathered those who supported her and attempted to usurp Asherah, an act that exiled her to the lower planes. For a hundred millennia she would plan, build her strength, and war with the other planes. She especially coveted the celestial throne of her former lover, but eventually an uneasy peace between the planes was struck. Hel would be given dominion of Bataar and the lower planes. Additionally she was given authority to judge evil, chaotic, or rebellious souls. Those she could not reform and conscript she locked up in the Abyss, later to be tormented into demons. In trade she guards the other realms from the worst malevolent spirits, keeping the Abyss away from all other realities.
Above all else Hel stands against chaos, believing only the strictest of control can ensure the preservation of creation. She has built strict caste systems around her, and she has little regard for beings of lesser power than her. Queen Hel is especially brutal when it comes to those who stand in her way, and is not known for an abundance of mercy. There is no atrocity she will not consider to ensure order, or to enhance her own power.
Bataar is a flat disk of a realm, each a hellish landscape in it's own right. Each ring is infinite in space, only surpassed by connective caverns, gates, or valleys. Only the first ring of Bataar is accessible to the other planes. The Abyss, realm of demons and malevolent spirits sits in the very center, guarded by a ring of mountains and glaciers in the ring around it called Helheim. Seven of the rings of Bataar are ruled over by devil princes, fallen angels that followed Hel in her rebellion. Hel herself rules all from her frozen seat in Helheim.
To learn more about Hel, the rings of Bataar, or the seven princes check the articles below.