Angrbodr
Angrbodr is the Jotun who mothered Loki's three monstrous children; Fenrir, Hel and Jormangandr, by Loki.
She lived in the IronWood, a deep dark wood upon Midgard. When her children we're taken to Asgard, little is known about what happened to her afterwards. She was not seen at Ragnarok and is presumed dead.