Banshee

"Where the mummy had been was a woman with floor length black hair and a skeletal, green-tinged face — a banshee. She opened her mouth wide and an unearthly sound filled the room, a long, wailing shriek that made the hair on Harry's head stand on end —"

- A boggart impersonating a banshee

The Banshee (Gaelic spelling beannsidhe) is a Dark creature native to Ireland and Scotland. Banshees have the appearance of women and their cries are fatal to anyone that hears them.

History
The Bandon Banshee was supposedly defeated by Gilderoy Lockhart, which he described in his book Break with a Banshee; though he admitted to stealing credit for his books. The only thing known about the actual witch who defeated the Bandon Banshee was that she had a hairy chin.

Seamus Finnigan was afraid of Banshees, as his Boggart demonstrated. Seamus also mentioned it when Harry Potter opened the golden egg and heard a screeching sound.

The singer Celestina Warbeck is known to perform with a backing group of banshees. Another possible banshee was the Bogle-banshee, mentioned by a student on the "Second Year Essential Knowledge Test" that Gilderoy Lockhart gave his second year Defence Against the Dark Arts class in 1992.

The Banshee was not mentioned in Fantastic Beasts and Where to find them although Newton Scamander may have left them out because of their similar looks to humans or maybe he didn't believe they existed because he never saw one.

Biology and description
Banshees have the appearance of a woman with floor length black hair, a skeletal face, and green skin. A banshee's scream is fatal to the ears, in a manner similar to fully grown Mandrakes.

Behind the scenes

 * Mrs. Mason "screamed like a banshee" when the owl post letter warning Harry Potter about his supposed Underage magic transgression (actually committed by Dobby) was dropped on her head.

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Goblet of Fire
 * Daily Prophet Newsletters
 * Wonderbook: Book of Potions
 * Pottermore

Notes and references
Banshee Spectre de la mort Banshee Банши Szyszymora