is a female spirit in Irish mythology, usually seen as an omen of death and a messenger from the Otherworld. Her Scottish counterpart is the bean shìth (also spelled bean-shìdh). The aos sí ("people of the mounds", "people of peace") are variously believed to be the survivals of pre-Christian Gaelic deities, spirits of nature, or the ancestors. Some Theosophists and Celtic Christians have also referred to the aos sí as "fallen angels". They are commonly referred to in English as "fairies", and the banshee can also be described as a "fairy woman".

In Irish and Scottish legend, a banshee wails around a house if someone in the house is about to die. There are particular families who are believed to have Banshees attached to them, and whose cries herald the death of a member of that family.

Traditionally, when a citizen of an Irish village died, a woman would sing a lament at their funeral. These women singers are sometimes referred to as "keeners". Legend has it that, for five great Gaelic families: O'Gradys, O'Neills, O'Briens, O'Connors, and Kavanaghs, the lament would be sung by a fairy woman; having foresight, she would appear before the death and keen. When several banshees appeared at once, it indicated the death of someone great or holy. The tales sometimes recounted that the woman, though called a fairy, was a ghost, often of a specific murdered woman, or a woman who died in childbirth.

Banshees are frequently described as dressed in white or grey, and often having long, fair hair which they brush with a silver comb. This comb detail is also related to the centuries-old traditional romantic Irish story that, if you ever see a comb lying on the ground in Ireland, you must never pick it up, or the banshees, having placed it there to lure unsuspecting humans, will spirit such gullible humans away. Other stories portray banshees as dressed in green, red or black with a grey cloak.

Etymology

The term banshee is an anglicization of the Irish bean sí, or the Scots Gaelic bean shìth, - both meaning "woman of the fairy mounds" or "woman of peace". Both names are derived from the Old Irish ben síde: bean: "woman", and sídhe: "of the mounds".

Some consider the bean nighe ("washer-woman") the Scottish counterpart of the Irish banshee. However, bean shìth is the linguistic and mythological equivalent, appearing in a number of different roles and situations in folklore and mythology. The bean nighe is a specific type of bean shìth.

In Scottish Gaelic, bean shìth can also be spelled bean-shìdh. Both are correct.

Síd in Irish, and Sìth in Scots Gaelic, also mean "peace", and the fairies are also referred to as "the people of peace" - Aos Sí or Daoine-Sìth.