Achilles

Achilles was a Greek hero of the Trojan War and the central character and greatest warrior of Homer's Iliad. Achilles was said to be a demigod; his mother was the nymph Thetis, and his father, Peleus, was the king of the Myrmidons.

Achilles’ most notable feat during the Trojan War was the slaying of the Trojan hero Hector outside the gates of Troy. Although the death of Achilles is not presented in the Iliad, other sources concur that he was killed near the end of the Trojan War by Paris, who shot him in the heel with an arrow. Later legends state that Achilles was invulnerable in all of his body except for his heel. Because of his death from a small wound in the heel, the term Achilles' heel has come to mean a person's point of weakness. 

Zeus and Poseidon had been rivals for the hand of Thetis until Prometheus, the fore-thinker, warned Zeus of a prophecy that Thetis would bear a son greater than his father. For this reason, the two gods withdrew their pursuit, and had her wed Peleus.

When Achilles was born Thetis tried to make him immortal, by dipping him in the river Styx. However, he was left vulnerable at the part of the body by which she held him, his heel.