Sometimes spelled Polyphemus. The specific one-eyed monster that the Ithakans encounter on their way home. Unfortunately for everyone involved, Polyphemos eats human flesh. Doubly unfortunately, Polyphemos is Poseidon's son. Once the Greeks blind him and make their escape, Polyphemos calls in a favor from daddy. This means years and years of torture for Odysseus (and his men, until they die). Basically, Polyphemos is the explanation for Poseidon's outrage at Odysseus.