The Morrígan ("phantom queen") or Mórrígan ("great queen"), also written as Morrígu or in the plural as Morrígna, and spelt Morríghan or Mór-ríoghain in Modern Irish, is a figure from Irish mythology who appears to have been considered a goddess, although she is not explicitly referred to as such in the texts.
The Morrígan is a goddess of battle, strife, and sovereignty. She sometimes appears in the form of a crow, flying above the warriors, and in the Ulster cycle she also takes the form of an eel, a wolf and a cow. She is generally considered a war deity comparable with the Germanic Valkyries, although her association with a cow may also suggest a role connected with wealth and the land. Wiki.
The Morrigan frequently appears in the ornithological guise of a hooded crow. She is one of the Tuatha Dé Danann ("Tribe of the goddess Danu") and she helped defeat the Firbolg at the First Battle of Mag Tuireadh and the Fomorians at the Second Battle of Mag Tuireadh.
The origins of the Morrigan seem to reach directly back to the megalithic cult of the Mothers. The Mothers (Matrones, Idises, Disir, etc.) usually appeared as triple goddesses and their cult was expressed through both battle ecstasy and regenerative ecstasy. It's also interesting to note that later Celtic goddesses of sovereignty, such as the trio of Eriu, Banba, and Fotla, also appear as a trio of female deities who use magic in warfare. "Influence in the sphere of warfare, but by means of magic and incantation rather than through physical strength, is common to these beings." (Ross 205)
Eriu, a goddess connected to the land in a fashion reminiscent of the Mothers, could appear as a beautiful woman or as a crow, as could the Morrigan. The Disir appeared in similar guises. In addition to being battle goddesses, they are significantly associated with fate as well as birth in many cases, along with appearing before a death or to escort the deceased. Pantheon.org