The banshee is a female spirit, and her keening heralds the demise of a family member. It is said that only the descendants of the Milesians, (surnames such as prefixed with O’ and Mac) have family banshees. Other beliefs consider that each family member has their own banshee.
The banshee can appear in many forms including: wearing a gray cloak over a green dress with long streaming hair and red eyes; a pale woman in a white dress with red hair; a woman in a sliver dress with silver hair; a beautiful woman in a shroud; a headless woman naked from the waist up and carrying a bowl of blood; or an old woman dressed in black wearing a veil.
Her stature is another physical description that varies. Most accounts describe the banshee as between one and four feet in height, while few accounts describe her as unnaturally tall.
Regardless of her appearance, she will wail when a family member died or is about to die. Her warning will come even if the family member is far away, or if someone is about to enter a deadly situation and they are unlikely to survive.
It’s important to note that banshees are not necessarily evil entities. Some banshees appear as beautiful women and sing mournful songs in the days preceding the death of a family member. Often, the only person who can hear her song is not long for this world. However, there are other accounts which talk of evil banshees that actively seek their victims and wail until they drive the person insane or to commit suicide.