Hild
Hild (ヒルド Hirudo?) is a character in anime/manga series Oh My Goddess! The ultimate Demon in Hell, known as the Daimakaichō (Great Demon Leader, Ruler of Demonkind in the dub), and also Urd's (who she refers to as "Urd-chan" (Urdie in the dub) mother. She is incredibly powerful, with her power dwarfing even the combined strength of the three goddesses. In the manga, she makes her first appearance in volume 21; in the season 1 of anime, she was only been seen in shadow, once during a flashback by Urd and another time in the credits for the final episode of the TV series. In second season, she makes her appearance at episode seventeen. Later on, Hild leaves behind an avatar (a child version of herself) who would go on to become a regular antagonist for the goddesses, as well as a direct supervisor for Marller. While this avatar possesses only one thousandth of the true Hild's power, it is still enough to make the avatar a powerful enemy for anyone. - From Wikipedia