Polyphemus is the most famous of the Cyclopes - giant monsters with a single eye - in Greek mythology. He was the son of Poseidon and Thoosa. He is mentioned in Homer's Odyssey where he is described as living in a cave and eating raw flesh - including humans. He also kept a flock of goats and sheep.
Polyphemus was the Cyclops who captured Odysseus and his men, keeping them in his cave and eating them two-by-two. The Greeks escaped by first blinding Polyphemus with a sharpened pole, then hiding under the belly of the giant's flock as they left the cave. Odysseus had tricked Polyphemus by telling him his name was "Outis" (the Greek for "nobody"), so when Polyphemus' brothers responded to his cries of pain, upon being blinded, he answered their calls of 'Who is hurting you?" with the reply, "Nobody is hurting me." Thinking that his screams were as a result of the gods punishing Polyphemus, the other Cyclopes left again.
After Odysseus had made his escape, Polyphemus prayed to his father for revenge, asking him to curse Odysseus, and for the remainder of Odysseus' voyage home, he had to contend with an angry Poseidon. 
- "Polyphemus." Encyclopedia Mythica from Encyclopedia Mythica Online.<http://www.pantheon.org/articles/p/polyphemus.html>[Accessed March 22, 2009].