This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Gaueko (Basque)
In Basque mythology, Gaueko does not allow humans to do certain works outside the house during the night. He especially punishes all those who try to show off as brave in the night, boasting of not fearing the darkness. In some cases he makes his presence felt as a gust of wind, as he pronounces these words: "the night for Gaueko (the one of the night), the day for the one of the day". Sometimes he appears in the shape of a cow, sometimes in that of a monster.
The Gaueko is often depicted as a great black wolfhound who sometimes walks upright like a human. He is also known to appear as a bull, monster or a gust of wind. Gaueko is also known for eating shepherds and their flocks. Gaueko’s howls can often be heard on cold winter nights. Gaueko is the male personification of the Night and all of its dangers.