The cyclops was a member of a primordial race of giants, each with a single eye in the middle of its forehead. The name is widely thought to mean "circle-eyed". In Greek mythology a cyclops was a giant man-eating monster, and was represented with only one eye. The most famous cyclops was Polyphemus, who was defeated by the hero Odyseuss.
These giants originated from three cyclopes who were also brothers. The three brothers were Brontes, Steropes and Arges, and their names meant thunderer, lightning and bright respectively. This cyclopes were the primordial sons of Ouranos and Gaia and were the brothers of the Hekatonkheir, making them brothers to the Titans and akin to the Olympians, and later deities alongside other creatures. According to Hesiod, they were strong, stubborn, and "abrupt of emotion". Time passed and eventually they became synonyms for brute strength and power, and they were often pictured at their forge.
The cyclopes helped Hephaestus at his forge, and were said to be responsible for the cyclopean fortifications at Tiryns and Mycenae in the Peloponnese. According to the hymn, the noises proceeding from the heart of volcanoes were attributed to the Cyclopes' activities.
Because of their showcasing of power, Ouranos feared the Cyclops and imprisoned them on Tartaros. They, along with the Hecatoncheir, supported Cronus in his coup d'etat to overthrow his father, but instead of freeing the Cyclopes and the Hecatoncheir, he kept them in Tartarus. They remained there, guarded by the dragon Campe, until they and the Hecatoncheir, were freed once and for all by their nephews; Zeus, Poseidon, and Hades. In gratitude, they aided the three brothers and fashioned Zeus' thunderbolts, Poseidon's trident and Hades' helmet of invisibility. To create Zeus' thunderbolt, Arges added the brightness, Brontes added the thunder, and Steropes the lightning. The cyclopes aided Zeus in his battle against the Titans and with their help, Zeus finally deposed Cronus, just as Cronus did to his own father Ouranos. The thunderbolt later became Zeus' trademark weapon and symbol.