- Achilles was the best Greek fighter besieging Troy
- His only weakness was his heel
- His mother had dipped him into the River Styx making the skin that touched the water invincible
- His mother forgot that she held him by his heel when she dipped him in the River Styx, thus leaving his heel the only vulnerable part of his body
- He was slain by Apollo
- Whenever someone has a weakness it's commonly referred to as their "Achilles Heel"