The Morrígan encourages warriors to do brave deeds, strikes fear into their enemies, and is portrayed washing the bloodstained clothes of those fated to die.
The Morrígan is described as the envious wife of The Dagda and a shape-shifting goddess,[14] while Badb and Nemain are said to be the wives of Neit.
[23] The Morrígan's earliest narrative appearances, in which she is depicted as an individual,[26] are in stories of the Ulster Cycle, where she has an ambiguous relationship with the hero Cú Chulainn.
In the Táin Bó Regamna ("The Cattle Raid of Regamain"), Cú Chulainn encounters the Morrígan, but does not recognise her, as she drives a heifer from his territory.
Later in the story, mortally wounded, Cú Chulainn ties himself to a standing stone with his own entrails so he can die upright, and it is only when a crow lands on his shoulder that his enemies believe he is dead.
In 12th-century pseudohistorical compilation the Lebor Gabála Érenn ("The Book of the Taking of Ireland"), she is listed among the Tuatha Dé Danann as one of the daughters of Ernmas, granddaughter of Nuada.
[11] According to Geoffrey Keating's 17th-century History of Ireland, Ériu, Banba, and Fódla worshipped Badb, Macha, and the Morrígan respectively.
After they have sex, the Morrígan promises to summon the magicians of Ireland to cast spells on behalf of the Tuatha Dé, and to destroy Indech, the Fomorian king, taking from him "the blood of his heart and the kidneys of his valour."
This connection is further noted by Patricia Lysaght: "In certain areas of Ireland this supernatural being is, in addition to the name banshee, also called the badhb".
"[45] Patricia Lysaght notes that the Cath Maige Tuired depicts the Morrígan as "a protectress of her people's interests" and associates her with both war and fertility.
[7] According to Proinsias Mac Cana, the goddess in Ireland is "primarily concerned with the prosperity of the land: its fertility, its animal life, and (when it is conceived as a political unit) its security against external forces.
"[12] Likewise, Maria Tymoczko writes, "The welfare and fertility of a people depend on their security against external aggression," and notes that "warlike action can thus have a protective aspect.
"[8] It is therefore suggested that the Morrígan is a manifestation of the earth- and sovereignty-goddess,[5][6] chiefly representing the goddess' role as guardian of the territory and its people.
[46] These were "bands of youthful warrior-hunters, living on the borders of civilized society and indulging in lawless activities for a time before inheriting property and taking their places as members of settled, landed communities.
[48] There is a burnt mound site in County Tipperary known as Fulacht na Mór Ríoghna ("cooking pit of the Mórrígan").
There may be a link with the three mythical hags who cook the meal of dogflesh that brings the hero Cú Chulainn to his doom.
The Dá Chích na Morrígna ("two breasts of the Mórrígan"), a pair of hills near Brú na Bóinne in County Meath, suggest to some a role as a tutelary goddess, comparable to Anu, who has her own hills, Dá Chích Anann ("the breasts of Anu") in County Kerry.
Other goddesses known to have similar hills are Áine and Grian of County Limerick who, in addition to a tutelary function, also have solar attributes.
There have been attempts by some modern researchers and authors of fiction to link the Morrígan with the character of Morgan, the latter often being depicted in the legend as a fairy or otherwise supernatural sister of King Arthur.
Morgan first appears in literature in Geoffrey of Monmouth's 12th-century Vita Merlini as a goddess-like figure in no blood relation to Arthur, whom she takes to her Otherworld style land of Avalon following his mortal wound in a battle.
In some Arthurian texts, such as Sir Gawain and the Green Knight, Morgan is portrayed as a hag whose actions set into motion a bloody trail of events that lead the hero into numerous instances of danger.
Morgan is also depicted as a seductress, much like the older legends of the Morrígan, and has numerous lovers whom she might even abduct for this purpose (as in some stories of Lancelot and Ogier the Dane, among others).