Greek mythology makes a distinction between the "lesser" Cyclopes, who were the sons of Poseidon, and the "elder" Cyclopes, who were children of Kronos. Their names were given as Arges, Brontes, Steropes, Euryalos, Elatreus, Trakhios and Halimedes. The Elder Cyclopes were known as craftsmen and builders, and were so feared for their great strength that they were kept locked in Tartarus.

"After ten years of fighting Ge prophesied a victory for Zeus if he were to secure the prisoners down in Tartarus as his allies. He thereupon slew their jail-keeper Kampe, and freed them from their bonds. In return the Cyclopes gave Zeus thunder, lightning, and a thunderbolt, as well as a helmet for Hades and a trident for Poseidon. Armed with these the three gods overpowered the Titans, confined them in Tartaros, and put the Hekatonkheires in charge of guarding them."

-- Apollodorus