Even though the banshee is usually represented as a dishevelled screaming female figure whose scream is an omen of death, her origins are far more complex and fascinating.
The name 'banshee' can be translated as 'fairy woman'. It comes from bean sìdhe or bean sìth, in Irish and Scottish Gaelic, which means 'female of the fairy folk' or 'female of the fairy mound'. The sìth people, according to John Gregorson Campbell in Gaelic Otherworld, refers to the whole fairy race, fairy and elfin people alike. As a substantive, sìth means 'peace' and, as an adjective, it only applies to objects of the supernatural world, especially to fairies and what belongs to them or is associated with them. Campbell writes: "The name sìth without doubt refers to the 'peace' or silence of Fairy motion, as contrasted with the stir and noise accompanying the movements and actions of men. The German 'still folk' is a name of corresponding import. The Fairies come and go with noiseless steps, and their thefts or abductions are done silently and unawares to men. (...) They seem to glide or float along rather than to walk." Hence the name duine sìth that means 'a man of peace, a noiselessly moving person, a Fairy, an Elf' of which bean sìth is the feminine form.
If we look into Irish mythology, it is said that when the Tuath Dé ('tribe of the gods'), supernatural race that encompass the pre-Christian Irish deities, were defeated, they were led underground into the sìdhe mounds. They became aes sìdhe, the people of the mounds, invisible to men. So the banshee or bean sìth, the fairy woman, is in fact the fallen form of the old Celts’ goddess.
The banshee is also undoubtedly linked to the Morrígan ('phantom queen') who appears in one version of Cúchulainn's death-tale as a hag washing his bloody armour in a ford, omen of his death, as Cúchulainn rides to meet his enemies. The bean sìth is known as bean nighe or 'washing woman' whenever she is seen beside a pool or a stream washing the linen of those who are soon to die.
Very much like Morgana who takes Arthur on his final journey to the magical island of Avalon in the Arthurian legend, or the Valkyrie who, in Norse mythology, chooses the men who may die in battle before taking them to Valhalla, the banshee eases the passage of men to the Otherworld. The fairy woman can be compared to the sacred women who used to sing the dying to sleep. It is said that each great Irish family and clan of the Highlands had a banshee that would warn them of a death to come by screaming or wailing. In The Woman's Encyclopedia of Myths and Secrets, Barbara G. Walker explains that “the shriek of the banshee was really the nocturnal call of the loon, a bird sacred to the Moon-goddess Luna, as its name suggests.” It is not hard to imagine, when you listen to it, how scared one must have felt should they have encountered it in the dark at night amongst the mist of Ireland or the Scottish Highlands...