Irish:
Bean Sidhe
Scots Gaelic:
Ban Sith

banshee, (“woman of the fairies”) supernatural being in Irish and other Celtic folklore whose mournful “keening,” or wailing screaming or lamentation, at night was believed to foretell the death of a member of the family of the person who heard the spirit. In Ireland banshees were believed to warn only families of pure Irish descent. The Welsh counterpart, the gwrach y Rhibyn (“witch of Rhibyn”), visited only families of old Welsh stock.

The Scottish novelist Sir Walter Scott mentioned belief in a kind of banshee or household spirit in certain Highland families (Letters on Demonology and Witchcraft, 1830).

Tuatha Dé Danann, (Gaelic: “People of the Goddess Danu”), in Celtic mythology, a race inhabiting Ireland before the arrival of the Milesians (the ancestors of the modern Irish). They were said to have been skilled in magic, and the earliest reference to them relates that, after they were banished from heaven because of their knowledge, they descended on Ireland in a cloud of mist. They were thought to have disappeared into the hills when overcome by the Milesians. The Leabhar Gabhála (Book of Invasions), a fictitious history of Ireland from the earliest times, treats them as actual people, and they were so regarded by native historians up to the 17th century. In popular legend they have become associated with the numerous fairies still supposed to inhabit the Irish landscape.