MORRIGAN

Morrigan, with your long red hair flying
And your tattered cloak the colour of blood
You screech across the battlefield in a raven's croak
Glorying in the slaughter, and feasting on the slain.
Morrigan is the red-haired Irish battle goddess of the Tuatha Dé Danaan, said to be one of the three daughters of Ernmas The meaning of her name is uncertain. It may derive from Mór Ríagan or Mór-Ríoghain [‘Great Queen’] or Morrigu [‘Queen of Nightmares’] or Mor-Ríoghain [‘Phantom Queen’]. She is a triple goddess incorporating the aspects Babd [‘Raven’], Nemain [‘Frenzy’] and Macha [‘Battle’]. The Morrigan gives warning of coming battles, urges on her chosen side, and finally takes the form of a crow or raven to feed upon the dead on battlefields. The heads of those killed in battle were dedicated to her.
Morrigan is the protectress of the land and also has functions as a goddess of agriculture and irrigation. A range of low hills known as the Paps of Morrighan is dedicated to her. The Dagda ['Good God'] discovered her on the Eve of Samhain [Halloween] before the Second Battle of Magh Tuiredh as she stood astride the River Unius, washing the bloody armour of those who were destined to die. While in this position, the two mated, perhaps indicating that the Morrigan has aspects as both a death and fertility goddess. She urinated a stream that irrigated the land.
It is possible that she was the original of the death herald, the banshee. Those warriors who heard the siren songs of the Morrigan were destined to die in battle, while those who did not might have wit enough to live. Thus, her song is an omen of death, like the wail of the banshee.
She was implacable and without mercy, but she liked to mate with both gods and human men, and could appear as a beautiful woman when she chose. The mighty hero Cuchulain excited her lust as she watched him wash himself, naked on the riverbank. She put on her finest clothes and a glamour so marvellous that she shone like the sun, approaching the warrior and inviting him to sleep with her. He shook his head, saying that he was too tired from the day's combat. She replied that she could help him in battle, and thereby save his strength for more interesting things, but he laughingly scorned the help of a woman. And it was this that roused her ire and from then on, she was his implacable enemy and determined to bring about his downfall.
As Cuchulain watched, a wagon approached, drawn by a single bright red horse walking upon three legs. Alongside it walked a footman holding a forked hazel wand. In the wagon was a woman with hair like bright red flames, wearing a red cloak. Red is associated with death and the Underworld in Celtic myth, and this apparition of the Morrigan in red was an omen of Cuchulain's death. Suddenly everything disappeared except the woman, who became a great black bird, and flew away.
The next day on the battlefield, the Morrigan took the form of a red heifer without horns, which caused confusion amongst Cuchulain's men and gave an advantage to the enemy. Cuchulain was forced into a stream, and the Morrigan changed herself into an enormous black eel, and twisted herself about Cuchulain's body, so that he almost downed. Just as he was about to untangle himself, she shapeshifted into a wolf and savaged him badly. The Morrigan didn't get the fight all her own way, however, and had to retire from the fray injured.
Knowing that she must be cured by the one who had wounded her, she disguised herself as an old woman with a milking pail, sitting with a red cow by the side of the road where Cuchulain must pass, on his way home. When he appeared, she offered him a cup of milk, and he took it, calling a blessing on the hag. She gave him a second cup, and again he drank, offering a second blessing. A third time he drained the milk from the cup, and offered a third blessing. This threefold benediction completed the cure and the Morrigan turned into a raven, lying into the air with a mocking caw. She perched on a thorn bush and prophesied his death.
Cuchulain met his end after being forced by three hags (the Morrigan in her triple aspect) to break his geis of eating dog flesh. She watched as he lay dying, an otter lapping his blood.
NB: This short article is not from my more comprehensive Goddess Encyclopaedia