Most likely Being
The Banshee (Gaelic spelling beannsidhe) is a Dark creature.
Biology and Description
A banshee had the appearance of a woman with floor length black hair, and a skeletal green tinged face.
The Bandon Banshee was supposedly defeated by Gilderoy Lockhart, which he describes in his book Break with a Banshee; though he admits 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.
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.
Protection from Banshees
The only known way to stop a banshee is to break its neck when it closes its eyes to scream, because every other part of its body is as tough as steel.
Powers and Abilities
A notable power of a banshee is a high-pitched supersonic scream that can kill anyone. A banshee's fatal scream is very similar (if not the same) to a fully grown Mandrake's scream, which is also fatal. 
- Harry Potter and the Philosopher's Stone (video game)
- Harry Potter and the Chamber of Secrets (Mentioned only)
- Harry Potter and the Chamber of Secrets (film) (Mentioned only)
- Harry Potter and the Chamber of Secrets (video game)
- Harry Potter and the Prisoner of Azkaban (Seen as boggart)
- Harry Potter and the Goblet of Fire (Mentioned only)
- Daily Prophet Newsletters
- Pottermore (Appears on book cover)