This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Cheval Gauvin (French)
The Cheval Gauvin (French: Gauvin horse) is a legendary evil horse of Franche-Comté, France and the Jura Mountains in Switzerland. It is said to wander along watercourses, through forests and graveyards, and to attempt to kill those who ride it, either by drowning them or throwing them into an abyss.
In Switzerland, the horse gallops through villages and abducts young girls. Several legends are attached to it, one of which makes it the mount of the medieval lord Amauri III de Joux. A woman's account of meeting him in the Chamblay cemetery has been commented on and told since the 19th century. A harbinger of death, the Gauvin horse seems to have acted as a bogeyman for children.