What were the hundred-handed giants called who helped Zeus?

The hundred-handed giants who helped Zeus were the Hecatoncheires.

Greek mythology describes the Hecatoncheires as three brothers—Cottus, Briareus, and Gyges—each possessing fifty heads and one hundred arms. They were children of Uranus, the sky, and Gaia, the earth, alongside the Titans and the one-eyed Cyclopes.

Uranus imprisoned them beneath the earth, and later Cronus kept them confined. Before the Titanomachy, Zeus released the brothers and restored their strength with nectar and ambrosia. They then fought beside Zeus and the Olympians, hurling enormous rocks at the Titans while Zeus attacked with his thunderbolt.

The name means “Hundred-Handers,” although Hesiod usually identifies the brothers by their individual names rather than using the collective term. They are often confused with the Gigantes, another group of giants who fought the Olympians in the later Gigantomachy. After the Titans’ defeat, the Hecatoncheires were associated with guarding them in Tartarus.