Mr. Ixolite, a member of Reg Shoe's Fresh Start Club in Ankh-Morpork, is reputedly the last surviving banshee on the Disc. Supposing for the sake of argument that we do have more banshees in the world, the characteristics are:
- All banshees are pale, thin, tall humanoid creatures with very large leathery wings that, at a casual glance, look like a black cape.
- Hearing the screech of a banshee means one is going to die.
- If the screech is from a civilized banshee, the reason for the above is that the banshee happens to know one is going to die, and custom demands that he/she should screech to warn you.
- the wild banshee has a more direct approach, if you hear its screech you know you're going to die because it will be the cause of your death.
- Wild banshees, if they do exist, also eat all manners of things, such as their dear old granny, or toxic Ankh-Morporkian pigeons.
- It is likely that while in decline, just enough of a breeding population of wild banshees exists in Lipwig to be a menace to its human population. As demonstrated by Moist von Lipwig in Going Postal, Lipwiger children are routinely taught how to identify the presence of a banshee; whether or not it is interested in you; that if it is interested in you it is for one thing only; and most crucially, the proven strategy for fighting back, if attacked. If there were no banshee problem in Lipwig, then why pass this folklore onto children as one of those potentially life-saving skills?
The banshee (bàn sidh, bhan sidhe) is the spirit of death in old Ireland. The name meaning "spirit woman" or "fairy woman" (sidhe having associations with a fairy folk having much in common with Discworld elves), the banshee could take two forms. One was of an old crone crying bitterly as she washed clothes at a riverbank. If she saw you watching her, she would seek to either hit you with the robe she was washing (in which case, your own death was near) or to merely splash you with the dripping water (in which case, the death of somebody else in the family was close).
The noble Anglo-Irish families developed a banshee tradition closer to the Discworld variety: a consensus banshee appeared from the 16th century onwards, taking the form of a hunched bird-like entity that would sit on the roof of a house and moan and scream to herald a death inside. (This may also have borrowed from the classical latin-Greek concept of the lamariae, creatures who fulfilled a broadly similar role in classical culture, and the Eurypides, the bird-like furies of Greek legend). See also the Disc version of the Furies.