A female death-messenger in Celtic and Irish folklore, the banshee, is also known as Badhbh Chaointe, Ban Shee, Beansidhe, or Bean Sidhe.
It is the duty of the banshee to foretell the death of an individual, and it is said that the banshee particularly attended the male members of noble families, and she conveyed her message of death by means of a scream. She could appear as an old woman, a young girl, or a washerwoman.
From the old tales we know that the screams of a banshee could be heard throughout wide distances, but most often, they would only be seen near water. The appearance of this death-messenger close to a river or a lake, points to her identity as a washerwoman and the activity linked to that identity: namely, her washing. In all these respects, the banshee bears close resemblance to the Irish deities Mórrígan and the Badb.
Tradition-bearers and commentators have occasionally looked to fairy-lore and ghost-lore to explain the origin of the banshee, tending to view her simply as either a fairy woman, or just a restless female spirit in some way connected to the family for which she forebodes or proclaims death. However, closer analysis highlights folk-perceptions and traits that point to another, and quite different, source of the supernatural death-messenger belief: the two female figures in early Irish mythology, Mórrígan and the Badb.
Understanding the true origin of the banshee’s myth it’s important because it settles the nature and traits of this supernatural being. Many referred to the banshee as a fairy-woman, but nothing in the nature of this being supports such notions. Fairies are social beings that live in communities, and often have relationships with human beings, and their world. The death-proclaiming banshee, in contrast, is a solitary being that, although might be linked to a particular family, does not have a relation with any member of that family. Furthermore, banshees are never associated with one another, nor they form communities like the fairy race in general.
In respect to the banshee being a restless spirit, we must mention that while most spirits that remain in the physical plain had a particular reason to do so (most often unfinished business such as revenge or the need to protect a living person), banshees are not associated with such tasks, nor are they bringers of death and misfortune (as many angered spirits), they are simply announcers of death, filling the function of a prophet and not that of a binder of fortunes.
About the shape-shifting abilities of the banshee, some modern text mention that banshees can take the shape of some animals, birds in particular. However, according to Patricia Lysaght in her book “Aspects of the Earth-Goddess in the Traditions of the Banshee in Ireland” (1996), none of the established folk tradition in Ireland mentions that the death-messenger —banshee or badhbh— appeared in the shape of any bird. Nor is she imagined to appear in the shape of any animal or insect.
-Illes, J. 2009. Encyclopedia of Spirits: The Ultimate Guide to the Magic of Fairies, Genies, Demons, Ghosts, Gods, and Goddesses. Harper Collins: New York.
-Lysaght, P., 1996. Aspects of the Earth-Goddess in the Traditions of the Banshee in Ireland. The Concept of the Goddess, p.152.