This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Humbaba (Akkadian)
Humbaba, was a figure in Mesopotamian mythology and the origin and meaning of his name are unknown. He was portrayed as a figure comparable to an ogre, giant or demon. He is best known from myths focused on the hero Gilgamesh, including short compositions belonging to the curriculum of scribal schools, various versions of the Epic of Gilgamesh, and additionally Hurrian and Hittite adaptations.
He is invariably portrayed as the inhabitant or guardian of the cedar forest to which Gilgamesh ventures with his companion Enkidu. They clash, which leads to the death of Humbaba. The event typically causes the anger of the gods. He is also attested in other works of Mesopotamian literature. Multiple depictions of him have also been identified, including combat scenes and apotropaic clay heads.