Mu shuvuu is a demonic bird-like monster found in both Turkish and Mongolian folklore. Like many demons in folklore, they are actually a type of damned soul, born from unhappy mortals who have been transformed in death into monsters that prey upon the living. They are similar to the various types of vampire found in many other world mythologies.
Mu shuvuu (translating as "harmful bird") would manifest as a young girl with a sharp beak they would use to suck out the blood of their victims, having a tendency to try and hide these beaks with either their hands or in a veil.
They often prey on travellers or lonely hunters and were believed to be created when a girl died young (especially if she never experienced love) or via violence.