Rider-class Servant first seen in Fate/Apocrypha as the Rider of "Red" servant of Cabik Pentel. The greatest hero of the Trojan War, and was responsible for slaying Hector. When he was a child, his mother Thetis submerged his entire body into the river Styx to give him invulnerability, except for his heel where she held him. Achilles is thus killed by Hector's brother Paris when he shot an arrow at his heel.
The term "Achilles' heel", meaning a weakness in someone who otherwise has a strong constitution, is attributed to this mythology.
