Hagravens are a sort of combination between an old crone and a bird. They have clawed feet and hands and feathers growing out of their forearms. They will attack from afar with destruction spells and up close with their claws. They can be found in the company of Forsworn or Witches who serve them.
Young witches become Hagravens as a sacrifice of their humanity and beauty in order to acquire vast magical power. It is evident in the personalities and attitudes of Hagravens that they are not entirely content with their fateful, and irreversible, choice.
The Glenmoril Witches are residents of Glenmoril Coven. There are 5 of them in total and their coven was responsible for giving The Companions the Beast Blood. They were eventually wiped out by the Dragonborn who took their heads as a cure for lycanthropy.