This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Gigelorum (Scottish)
A Gigelorum is a legendary insect from Scottish folklore that was believed at the time to be the smallest possible living creature, so small that elders believed that a Gigelorum could live happily in the "ear of a mite". The term has since been used to refer to anything that is impossibly small. Gigelorum are completely harmless, indeed due to their extremely tiny scale most humans would be completely unaware of their existence without the aid of microscopic vision.