In Irish folklore, the Bean Sidhe (woman of the hills) is a spirit or fairy who presage a death by wailing. She is popularly known as the Banshee. She visits a household and by wailing she warns them that a member of their family is about to die. When a Banshee is caught, she is obliged to tell the name of the doomed.
The antiquity of this concept is vouched for by the fact that the Morrigan, in a poem from the 8th century, is described as washing spoils and entrails. It was believed in County Clare that Richard the Clare, the Norman leader of the 12th century, had met a horrible beldame, washing armor and rich robes "until the red gore churned in her hands", who warned him of the destruction of his host.
The Bean Sidhe has long streaming hair and is dressed in a gray cloak over a green dress. Her eyes are fiery red from the constant weeping. When multiple Banshees wail together, it will herald the death of someone very great or holy. The Scottish version of the Banshee is the Bean Nighe.
Aiobhill is the banshee of the Dalcassians of North Munster, and Cliodna is the banshee of the MacCarthys and other families of South Munster.
Also Banshi and Benshee. One of the household spirits of certain Scottish Highland or Irish families, supposedly a female creature that is said to wail at or before the death of a family member. The word is supposed to be derived from the Old Irish ben sidhe, a woman of the fairy folk, or 'woman of the fairy mound', but it is translated by different scholars in a variety of ways, including Female Fairy, Angel of Death, Lady of Death, Woman of Peace, White Lady of Sorrow, Nymph of the Air, and Spirit of the Air, amongst others.
The tradition of Banshee, which goes back to the early eight century, is currently alive and well in various parts of Ireland. Many people have described the 'terrible wail' which precedes a death and certain families are traditionally believed to be 'followed' by the Banshee. The word is sometimes also used to denote a sort of demon, but in Nordic folklore the Banshee is always benevolent.
The Banshee of legend is actually a disembodied soul, either of someone who in life was strongly attached to the family or who hated all its members. So, if she loves those whom she calls, the wail is a soft, tender, soothing chant, intended to either give notice of death's proximity and reassure the one destined to die, or to comfort the survivors. But if instead the Banshee during her life was a enemy of the family, the wail is more like the scream of a fiendish ghost, a demonic howling of delight over the coming fatal agony of one of her foes.