This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Glaistig (Scottish)
The glaistig is also known as maighdean uaine (Green Maiden), and may appear as a woman of beauty or monstrous mien, as a half-woman and half-goat similar to a faun or satyr, or in the shape of a goat. The lower goat half of her hybrid form is usually disguised by a long, flowing green robe or dress, and the woman often appears grey with long yellow hair.
The Glaistig is a shapeshifter and can appear as a goat or as a woman from the waist up, with her lower half that of a goat. Sometimes half-woman, half-goat, she may take the form of a beautiful woman, especially one already known to the male victimshe leaves her male victim with his throat cut, every drop of blood sucked from him.