The Cyclopes (Cyclops) were gigantic one eyed monsters. The most famous is Polyphemus, the Cyclops blinded by
The Cyclops are generally mentioned as the sons of Uranus and Gaea, but Homer speaks of Polyphemus, the chief of the Cyclops, as the son of Poseidon, and states the Cyclops to be his brothers. They were a wild race of gigantic growth, similar in their nature to the earth-born Giants, and had only one eye each in the middle of their foreheads. They led a lawless life, possessing neither social manners nor fear of the gods, and were the workmen of Hephaestus, whose workshop was supposed to be in the heart of the volcanic mountain Aetna.
Here we have another striking instance of the manner in which the Greeks personified the powers of nature, which they saw in active operation around them. They beheld with awe, mingled with astonishment, the fire, stones, and ashes which poured forth from the summit of this and other volcanic mountains, and, with their vivacity of imagination, found a solution of the mystery in the supposition, that the god of Fire must be busy at work with his men in the depths of the earth, and that the mighty flames which they beheld, issued in this manner from his subterranean forge.
The chief representative of the Cyclops was the man-eating monster Polyphemus, described by Homer as having been blinded and outwitted at last by Odysseus. This monster fell in love with a beautiful nymph called Galatea; but, as may be supposed, his addresses were not acceptable to the fair maiden, who rejected them in favour of a youth named Acis, upon which Polyphemus, with his usual barbarity, destroyed the life of his rival by throwing upon him a gigantic rock. The blood of the murdered Acis, gushing out of the rock, formed a stream which still bears his name.
Hesiod mentions only three (not a race or tribe): Arges (thunderbolt), Steropes (lightning), and Brontes (thunder), obviously storm gods. They were also the first smiths. When Cronus came to power he imprisoned the Cyclopes in Tartarus. The were released by Zeus and fought with him against the Titans. As a reward for their release the Cyclopes gave Zeus his weapons of lighting and thunder. They continued as his workers at Mount Olympus
forging his thunderbolts
Arges was killed by Hermes while he guarded Io for Hera
Apollo killed at least one of the Cyclopes to retribution
for Zeus killing his son Aesculapius.