Patroclus, in Greek mythology, dearest friend of the hero Achilles whom he accompanied to the Trojan War. In the tenth year of the conflict Achilles withdrew his troops, the Myrmidons, from combat because of a quarrel with Agamemnon, commander of the Greek forces. Without Achilles, the Greeks began to lose to the Trojans. Finally, as the Trojans began to burn the Greek ships, Patroclus persuaded Achilles to allow him to lead the Myrmidons to the rescue. Clad in Achilles' armor, Patroclus led the Greeks to victory, forcing the Trojans back to the walls of their city. In his moment of glory, however, Patroclus was slain by the Trojan commander, Hector. To avenge his friend's death, Achilles rejoined the battle and killed Hector.