A cyclops is a member of a race of giants, each with a single eye in the middle of his forehead. They are only mentioned in Young Hercules canon, but have been seen as real creatures in both Hercules: The Legendary Journeys and Xena: Warrior Princess.
Hesiod described three one-eyed Cyclopes, Brontes, Steropes and Arges the sons of Uranus and Gaia, brothers of the Titans, builders and craftsmen, while the epic poet Homer described another group of mortal herdsmen Cyclopes. Homer does not tell if they are one-eyed, this is assumed when Odysseus spins a beam in Polyphemus' eye. Other accounts were written by the playwright Euripides, poet Theocritus and Roman epic poet Virgil. In Hesiod's Theogony, Zeus releases three Cyclopes 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. In a famous episode of Homer's Odyssey, the hero Odysseus encounters the cyclops Polyphemus, the son of Poseidon and Thoosa (a nereid), who lives with his fellow Cyclopes in a distant country. The connection between the two groups has been debated in antiquity and by modern scholars. It is upon Homer's account that Euripides and Virgil based their accounts of the mythical creatures. - Cyclops - Wikipedia