This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Gashadokuro (Japanese)
The Gashadokuro takes the form of giant skeletons made of the skulls of people who died in the battlefield, and is 10 or more meters tall. Only the eyes protrude, and some sources describe them as burning yellow or green. Gashadokuro wanders around at 2:00 a.m. and attacks and eats humans when it sees them. When a Gashadokuro approaches, it is said to make a clattering sound with its teeth "Gachi Gachi" However they are also known to be stealthy when approaching humans they wish to eat.
The Gashadokuro are said to possess the powers of invisibility and indestructibility since it is composed of the bones of people who are already deceased, though Shinto charms are said to ward them off.Otherwise, a Gashadokuro will continue hunting its prey until its pent up anger is released, causing the bones to crumple and the Gashadokuro to collapse.