Colossal beings many thousands of metres tall, the Hecatoncheires were said to have each been possessed of one hundred hands and fifty heads. They were gifted with enormous physical strength, and had existed since before time began. The Hecatoncheires were named Briareos, Kottos and Gyges.
Born to the deities Uranus and Gaia, the Hecatoncheires were for some reason hated by their father and imprisoned along with their siblings the Titans and the Cyclopes in Tartarus. After the youngest of the Titans, Cronus, overthrew Uranus at the bidding of his mother and claimed rulership of the universe, they were briefly released, but soon re-imprisoned by Cronus as he feared that they would attempt to wrest his new domain back from him.
When Zeus launched his war against the Titans, he released the Hecatoncheires from their torment, and enlisted their aid. The mighty giants proved their worth in the conflict, hurling boulders the size of mountains fifty at a time at the Titans, and helping to bring about the ultimate victory of the Olympians.