In this Sci-Fi/Fantasy Writers Series I will provide sci-fi/fantasy writers with a wealth of information concerning subjects that they may wish to use in their work.
The series will name and describe some of the magical or fantastical creatures that you may want to use in your stories.
Banshee:

A banshee (“woman of the fairies”) is a 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.
The name banshee seems to be a contraction of the Irish Bean Sidhe, which is interpreted by some writers on the subject “A Woman of the Faire Race,” whilst by various other writers it is said to signify “The Lady of Death,” “The Woman of Sorrow,” “The Spirit of the Air,” and “The Woman of the Barrow.”
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.
Banshees may be divided into two main classes, the Friendly Banshees and the Hateful Banshees. The former exhibiting sorrow on their advent, and the latter, exultation. But these classes are capable of almost endless sub-division with the only feature they possess in common being that they are both female in nature. The cause of a banshee haunting is varied. Some authors suppose that banshees appear because of affection or a crime, but others point to an origin in sorcery and witchcraft.
Some writers portray banshees as very beautiful women—women with long, luxuriant tresses, either of raven black, or burnished copper, or brilliant gold, and whose star-like eyes, full of tender pity, are either dark and tearful, or of the most exquisite blue or grey; some, again, are haggish, wild, disheveled-looking creatures, whose appearance suggests the utmost squalor, foulness, and despair. Additionally, some stories portray banshees in the form of something that is wholly diabolical, frightful, or terrifying in the extreme.
As a rule, however, the banshee is not seen, it is only heard, and it announces its arrival in a variety of ways—sometimes by groaning, sometimes by wailing, and sometimes by uttering the most blood-curdling of screams. These screams are described as resembling those of a dying woman who was dying in a violent manner. Occasionally, banshees are described as clapping their hands, and tapping and scratching at walls and windowpanes, and, not infrequently, they are described as the signaling their arrival by terrific crashes and thumps.
Work Cited:
- Elliot O’Donnell, The Banshee, London And Edinburgh Sands & Company, 1907, In the public domain found at: https://www.gutenberg.org/cache/epub/34263/pg34263-images.html