This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Hecatonchires (Greek)
In Greek mythology, the Hecatoncheires, Hekatoncheires, or Hundred-Handers, also called the Centimanes were three monstrous giants, of enormous size and strength, each with fifty heads and one hundred arms. They were individually named Cottus, Briareus (or Aegaeon, the sea goat) and Gyges. In the standard tradition they were the offspring of Uranus and of Gaia, and helped Zeus and the Olympians to overthrow the Titans in the Titanomachy.
The Hecatoncheires are hated by their father Uranus and are sent into a dark hole within their mother Gaia along with the Titans and Cyclopes. Gaia convinces the Titan Kronos to castrate Uranus. Zeus leads an army along with the Hecatoncheires to take throne from Kronos and Zeus and the Olympians defeated the Titans and cast them into Tartarus. In some traditions, the Hecatoncheires then became the guards of the imprisoned Titans.