Achilles’ heel (and tendon)

Achilles, the hero of Homer’s Iliad, was invulnerable save for one part of his anatomy, his heel. According to legend, his mother Thetis, took him while still an infant, and dipped in the river Styx to make him impervious to all mortal wounds. However, the heel by which she held him remained untouched by the magic waters and he was eventually slain in the siege of Troy by an arrow that struck his heel. To this day the tendon running from the heel bone to the calf muscle of the leg is known as the Achilles’ tendon.