In Norse Mythology, Angerbotha is a giantess and the mother of Fenrir, Hel, and the Midgard Serpent with Loki.

It is more accurate to say that Angerbotha is the father of the three monsters and Loki is the mother. They were conceived after she had been burnt as a witch by the gods and Loki ate her heart. Her heart fertilized Loki and he became pregnant with the monsters and have birth to them.

Angerbotha is also spelled Angerboda or Angrboda.

Sources:
http://www.meta-religion.com/World_Religions/Ancient_religions/Europe/norse_mythology.htm
http://www.search.eb.com/ebi/article?eu=333457&query=angerbotha