Achilles, "the swift-footed," is the legendary hero of the Trojan War described in Homer's Iliad. Legend has it that as a child, he was bathed in the waters of the River Styx, which made him immortal. But since his mother held him by his heel when he dipped in, this remained his only vulnerable spot.
According to myth, during the Trojan War, Paris struck him in the heel with an arrow, guided by Apollo, causing his death.