Who blinded Polyphemus?

Polyphemus was the giant son of the god Poseidon and Thoosa in Greek mythology. He was one of the Cyclopes, having a single eye.

According to the "Odyssey", Odysseus arrived at the island of the Cyclops, while trying to go back to his homeland. There, he and his men went into a cave that was full of food. Polyphemus, who dwelled in the cave, returned and sealed the entrance so that none would escape; then he grabbed two of Odysseus' men and ate them. The next morning, he left to attend to his sheep, but not without eating two more of the men.

Upon his return, Odysseus offered him some strong wine, intoxicating him. Polyphemus, drunk, asked what the kind man's name was, and Odysseus replied "No one". Polyphemus fell into a deep sleep and Odysseus, having planned this, took a wooden stake and blinded Polyphemus' single eye. The giant started screaming for help, but when the other giants arrived, he told them "No one" had blinded him; his friends thought that a god had attacked him and told him to pray.