A Cyclop in Greek mythology and later, Roman mythology was a member of a primordial race of giants, each with a single eye in the middle of his forehead. The name is widely thought to mean "circle-eyed". These three one-eyed Titans forged thunderbolts for Zeus. Also any of a race of one-eyed giants, reputedly descended from these Titans, inhabiting the island of Sicily. In Hesiod's Theogony, Zeus releases three Cyclopes, the sons of Uranus and Gaia, from the dark pit of Tartarus. They provide Zeus' thunderbolt, Hades' helmet of invisibility, and Poseidon's trident, and the gods use these weapons to defeat the Titans.