Today we have a question about one of the most mysteriously badass ladies ever to cry havoc over the fields of Europe! I would love to hear more about the Morrigan - she is such a mysterious figure that we could all stand to learn more about! Indeed she is, friend.
The Morrigan is basically the personification of enigma; no one knows very much about her, neither mortals nor the other gods of her homeland of Ireland, except that she wields a great and mysterious power and is a force to be courted and feared. There's perennial argument over what her name means, since its roots are not totally clear and its etymology therefore up to scholar guesses, but most interpretations include either some variant on "queen" and/or some version of "terror" or "nightmare", which together give us a pretty handy sketch of what the Morrigan is all about.
Like the blackbirds that are her totem symbol, the Morrigan is a goddess associated with war, carnage, death and inevitability; she is not only called upon by warriors for aid in battle, in which she was considered to be the ultimate authority over the life or death of soldiers in combat, but also a seer who pronounces terrible omens and foresees death long before it occurs. She twists the fate of warriors so that their deaths or lives are in her hands; she can make it a person's unavoidable destiny to die on the battlefield if angered, or if pleased grant them a guaranteed victory.
Irish mythology suffered heavily from euhemerization brought on by the encroachment of Christianity, so we don't always know a whole lot about how the gods were actually worshiped; stories of their exploits survive in folktales, legends and the epic sagas of the Tuatha de Danann, who despite often being called mere mortals clearly perform divine and heroic feats, but worship of Celtic gods is more obscure and difficult to pin down. We're not really sure how or if the Morrigan was actively worshiped; certainly crows and ravens were probably sacred to her, and various gods and heroes call upon her to grant them frenzied powers on the battlefield or to forecast their victory, so we can guess that she was probably a figure called upon often in times of war.
For example, in one tale, the Dagda, god of fertility and masculinity, happens to come upon the Morrigan while she is bathing in the river Unis; because the gods plan to go to war with their rivals, the Fomorians, the next day, he asks for her blessing, which she grants on the condition that he has sex with her. Once he does, she tells him the battle plans of the Fomorians and instructs him on how to oppose them, and pledges herself to go forth and destroy the king of the Fomorians, whose blood she sheds ritually before the armies of the Tuatha to ensure victory. It's clear that the power of victory is the Morrigan's to grant, as she does to the Irish gods, or to take away, as she does to the Fomorians who have not sought her blessing.
Conversely, she is also quite capable of utterly destroying anyone who angers her, which she does in the myth of Cu Chulainn, one of the most famous and beloved heroes of Irish mythology. Upon seeing Cu Chulainn, she takes on the form of a beautiful woman and offers herself to him, but he tells her that he has no time for women since he is at war now. She then threatens him, telling him that if he spurns her he will be sorry when her powers come against him in battle, and he reacts by again refusing her, saying that whatever she brings against him he will simply destroy, and that he'll injure her herself if she dares to stand against him. She transformed herself into an eel to trip him while running, although he managed to keep his footing, and then into a wolf to savage him, but he managed to survive, and then into a heifer, which he wounded when she attempted to charge and trample him. The wounds Cu Chulainn inflicted on his enemies could not be healed without his blessing, so she therefore turned herself into an old woman and tricked him into granting her his blessing and reversing the injuries he himself had inflicted on her. Finally, she foretold that he would die in battle for his transgressions; and indeed, although he fought valiantly and all but singlehandedly won the war for his people, he eventually died standing up, and when the Morrigan's birds landed upon him and began to pick at him his enemies and allies alike knew he was truly dead.
As if she weren't doing enough things, the Morrigan is also the archetypal form of an Irish spirit called the bean nighe (or bannie, in modern spelling), the Washer at the Ford who appears as an old woman doing her laundry in a stream or river. Those who come too close to her run the risk of sealing their doom; if the clothes she is washing are clean, then no harm will come to them, but if the clothes are bloodstained, it means that whomever had the misfortune to see her will die soon thereafter. The Morrigan appears in this form in the Tain bo Cuailgne, and many of the later folkloric stories of the bean nighe (and its close cousin, the bean sidhe, better known to English speakers as the banshee) may be echoes of her long-ago tales.
The Morrigan is also interesting (like those stories weren't enough) because she is often held up as an example of the Celtic convention of the triple goddess - female divine figures that appear in sets of three and may be a single triplicate deity or three interlinked goddesses that function together as a unit. While the Morrigan herself is clearly the most central and important aspect of this triple goddess, appearing as a major character in many Irish myths, she is often depicted in ancient Celtic art along with two counterparts; some scholars interpret these as her alternate "selves", while others believe they are instead representative of an even greater horde of female figures standing behind her, akin to the valkyries of Norse mythology that follow the similar (although less scary) goddess Freyja.
Various different sources name other Irish goddesses as the Morrigan's "sisters" and therefore possibly parts of her divine triad; Lebor Gabála Érenn calls her sisters Macha and Anand, while the goddess Nemain appears in myths alongside the Morrigan to sow havoc in the ranks of enemies and is likewise paired with Badb, this time as co-wives of the ruler Neit, while in the same work later the goddess Fea is added to them as their third. All of these ladies are sometimes viewed by later scholars and writers as possible alternative aspects of the Morrigan herself, and indeed they are often concerned with the same things: war, doom, and the chaos of the battlefield.
The mainland Celtic peoples, by the way, have their own set of triple goddesses associated with destiny and prophecy, who were referred to by the Romans as the Matrones (the Mothers); it's very possible that they and the Morrigan are related, and took slightly different forms in the isles as opposed to on the mainland.
In fact, because of this apparent link between these goddesses, they are collectively called the Morrignu in twelfth- and thirteenth-century texts about ancient Irish religion, and some scholars have suggested that there may be no single figure of the Morrigan, but rather a class of goddesses, the Morrignu, that have interchangeable functions and can appear whenever and wherever they choose, and that tales of the Morrigan simply refer to one of these goddesses appearing and taking on the mantle of the warrior queen.
And speaking of Macha, who I mentioned up there, this particular possible "form" of the Morrigan also appears in various myths, the most famous being during the Tain bo Cuailgne when, while she was heavily pregnant, her husband boasted that the king's horses were so slow that even his gravid wife could outrun them. Seeking to humiliate him, the king demanded that Macha race his horses on foot; much to everyone's amazement, she not only outran all the horses, but then sat down on the finish line and gave birth to healthy twins. Furious at this treatment of her by all these dudes, however, she levied a prophetic curse on them, and said that in their hour of greatest needs they would all suffer the same pains of pregnancy and labor they had just inflicted on her, a prophecy that came true when the entire fighting force of Ulster was rendered unable to go to battle later in the saga and only Cu Chulainn was able to stand against their enemies.
Finally, in her most tragic myth, the Morrigan also gives birth to a divine child that is so hideous and fearsome at birth that the other gods become afraid that it will grow up to threaten them (it's possible that this baby is the result of her assignation with the Dagda, although it's never specifically said). They take the child from her and give it to the divine healer Dian Cecht, who cuts the baby open, but he discovers that there are three serpents inside its heart, which threaten to devour everything if they go unchecked. He then kills the serpents and burns them and the baby to ashes, and when he throws the ashes into the river Barrow, the river boils from the fearsome power of them even in death and kills every living thing along its length.
The Morrigan's response to this particular act is never addressed; we don't hear whether she is relieved or horrified, or whether she agrees with the decision to put the baby down or would have stopped it if she could. I feel like it's worthwhile to note that pretty much all of the Tuatha de Dannan except for her end up dying ignobly by the end of Irish mythology, though. Just saying.
The Morrigan is a classic case of the European idea of the Dangerous Goddess - her powers are mighty and uncontrollable by others, and this makes her a force to be feared, placated and avoided at all costs. Those powers she has that are considered "feminine" - disguise, childbirth, and manipulation of men - make her unconquerable, but unlike male war gods who are celebrated for their power, she is generally more feared than feted. The story of her offspring being cleansed and burned is an example of the classic mythological response to the Dangerous Goddess - she has to be controlled or she threatens everything simply by existing, so while she may have important powers and functions in the world, she is often considered almost an enemy in her own right regardless of her positive connotations.
But, like most warlike goddesses, there really is no controlling the Morrigan. She has all the power of destiny itself on her side, able to give or take life completely at her whim, and no sympathy or tenderness for those who oppose or insult her. Keep your eyes and ears away from the washers and howlers in the night, and tread lightly when you go to war!