Hecatonchires come from the Greek Hecatoncheires which means "hundred handed". They were gigantic and had fifty heads and one hundred arms each of great strength. There were three of them: Briareus also called Aegaeon, Cottus, and Gyges also called Gyes. They were of the same parents as the Titans and the Cyclopes, Uranus and Gaea (the Earth).
They were associated with the crashing of waves and earthquakes.
They participated in Gaia's rebellion against Uranus. When Cronus came to power he imprisoned the Cyclopes in Tartarus. Later, Zeus released both the Hecatonchires and the Cyclopes from the Underworld, where their father Uranus had imprisoned them.
For this reason they fought with Zeus against the Titans. With their hundred hands and tremendous strength and dexterity, they were able to hurl three hundred stones at one time at the Titans.
Being unable to overcome such a barrage, the Titans soon surrendered to Zeus. Zeus assigned the Hecatonchires to guard the Titans in Tartarus. One of them, Briareus, served as Zeus's bodygard.