The Cyclopes (singular Cyclops) were the three sons of Uranus and Gaia, the first king of the Titans. They were imprisoned by their father into the underworld, who feared their strength along with their three brothers, who had fifty heads and a hundred hands. Their names were Brontes, Steropes and Arges.
Cyclopes are usually shown as having one, round eye in place of where their two eyes should be, although sometimes they are depicted as having two empty eye sockets and an eye in the middle of their forehead. Sometimes they are depicted very ogre like,like other times depicted almost human.
The Cyclopes were known for their great strength, and also their ability of craftsmanship. They created Zeus' lightning bolts, in return for freeing them, while he was fighting the Titans. They also forged Poseidon's trident. They were also known for going around eating humans. They worked as Hephaestus helpers under the volcano Etna making Zeus's lightnings, but were killed by Apollo as a revenge for Zeus's killing his son Aclepius.
Other Information 
One of Poseidon's sons, Polyphemus, was a cyclops. Polyphemus plays an important part in the Odyssey, as one of the monsters that besets Odysseus and his crew on their way back to Ithaca. The Cyclopes were also the helpers of one of the gods after Zeus brought them out of the underworld.