Patroclus

In Greek mythology, as recorded in the Iliad by Homer, Patroclus, or Pátroklos (Gr. “glory of the father”), son of Menoetius, was Achilles’ best friend and, according to some (including Ovid), his lover.
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Noun
1. (Greek mythology) a friend of Achilles who was killed in the Trojan War; his death led Achilles to return to the fight after his quarrel with Agamemnon
(hypernym) mythical being
(classification) Greek mythology

[Greek heroic] The son of Menoetius (2), king of Opus in Locris. After the accident with his friend Clysonymus, the young Patroclus was taken to Peleus. Here he grew up with Achilles and became his closest friend. He followed Achilles to Troy as his brother-in-arms, and when Achilles refused to fight in order to annoy Agamemnon, Patroclus appeared in Achilles' armor at the head of the myrmidons and was slain by Hector. This made Achilles so angry, that he refused to rest until he had killed Hector, and honored his friend's death by solemn burial rites.