The Hecatonchires were born out of Gaea, the Mother Earth, and Uranus, the Heaven, during the creation of the world. There where three Hecatonchires in Greek mythology: Briareus, the Vigorous, Cottus, the Furious and Gyes, the Big-Limbed. All of them were strong, proud monsters, huge and terrible, each of them having hundred hands and fifty heads growing from their shoulders.
Gaea loved all her children without exception, even the Hecatonchires. Uranus, however, got scared on the mere sight of them and found their feature appalling and disgusting, so he decided to push them into the depths of Gaea, the Tartarus, making Gaea heave loud groans.
The Hecatonchires took later on revenge on Uranus by taking part in the Titanomachy (the battle of the Olympian gods against the Titans) , where they made use of their many hands to throw rocks at the Titans.