Who told Achilles that Patroclus's was dead?

Achilles learned of Patroclus's death from Antilochus, who was a messenger and a close friend. Antilochus informed Achilles that Patroclus had been killed by Hector during the Trojan War. This news prompted Achilles to seek revenge against Hector, driving the narrative of vengeance in Homer's "Iliad."