What made Achilles a hero?
Achilles was known for his invincibility. When he was born his mother dipped him in the River Styx holding him by the heel. This made him almost fully immortal, but if he was shot in the heel he would die. This fate came over him when Paris shot him in the heel in the Trojan War. The Greeks actually won that war in the end with the old give your enemy a wooden horse filled with Greek soliders ready to kill you trick. This is also why we have the Achilles tendon as a tendon in our heel.