There seem to have been two generations of Cyclopes. The first generation, described by Hesiod, were the sons of Gaia and Uranus. The three brothers, Brontes (thunderer), Steropes (flasher) and Arges (brightener), were clever and skilled in the art of metal working. Imprisoned by Uranus, they apparently were not set free by their brother Cronus. In the Titanomachy, they were set free by Zeus and aided the gods in battle. It was the Cyclopes who created the thunderbolt of Zeus. As a reward, Zeus allowed the Cyclopes to remain on Olympus and be his armorers. They also built the huge walls of Tiryns for the king Proetus.
The second generation, described first by Homer, dwelled in Sicily. They were the sons of Poseidon and a sea nymph. Unlike the first generation, they had no skill in iron working and did not follow the laws of man. The only notable Cyclops of the second generation is Polyphemus, who was outwitted by Odysseus in the Illiad.
Homer. The Iliad.