@duc i was thinking more Achilles, but sure, that also works :D
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 left heel (see Achilles' heel, Achilles tendon). en.wikipedia.org/wiki/Achilles#Birth_and_early_years