Odysseus brings twelve men with him to the Cyclops’ cave.
The episode occurs in Book 9 of Homer’s Odyssey, when Odysseus and his surviving crew reach the land of the Cyclopes. Rather than taking everyone from the ship, Odysseus selects twelve of his best companions to investigate a large cave. The rest remain behind to guard the ship. This detail makes the answer twelve men, not twelve people including Odysseus.
The cave belongs to Polyphemus, the one-eyed son of Poseidon. Odysseus and his companions enter hoping to receive the customary gifts owed to strangers, but Polyphemus rejects the rules of hospitality. He traps them by rolling a huge stone across the entrance and begins eating the men inside.
Odysseus eventually devises an escape. He gets Polyphemus drunk with wine, tells him that his name is “Nobody,” and blinds him with a sharpened stake. The surviving Greeks escape beneath the bellies of sheep. Odysseus’s later boast of his real name allows Polyphemus to identify him and ask Poseidon to punish him, prolonging the hero’s troubled voyage home.