Who is Achilles?
Achilles was the son of Peleus and Thetis: Peleus was a king in Greece, and Thetis was a nymph.
When Achilles was still a little baby, his mother tried to protect him from harm by dipping him into a river that had special magic water. And it worked; he could not be harmed, except for one heel that his mother held him by as she dipped him in the water. Now when someone is very strong but has one weak spot, we call that their "Achilles' heel." (This story is related to an Indian story from about the same time of Krishna and Duryodhana from the Maharabata, and to the later medieval story of Siegfried. Maybe all three stories come from an earlier Indo-European story, or maybe these people just heard each others' stories.)
When he grew up, Achilles heard a prophecy. It was this: he could make a choice to live quietly and without fame or honor, and live a long time and die in bed, or he could choose to be famous in his lifetime and remembered always, but to die young. What would you choose?
Achilles chose to be famous and die young. He lived through the events of Homer's Iliad, but then (according to some stories), killing the Trojan prince Hector, but then Hector's youngest brother, Paris, shot Achilles in the heel with an arrow and killed him.
The Iliad of Homer (Oxford Myths and Legends), by Barbara Leonie Picard. A retelling of the story.
The Iliad (Penguin Classics) by Homer. Translated by Robert Fagles. A great translation!
Approaches to Teaching Homer's Iliad and Odyssey, by Kostas Myrsiades (1987).
Achilles, by Mike Chapman (2004). A brief biography of Achilles, with details that aren't in the Iliad about Achilles' childhood.
Achilles in Vietnam: Combat Trauma and the Undoing of Character, by Jonathan Shay (1995). A best-seller, about the relationship between the rage of Achilles and PTSD in Vietnam vets.
Or check out the Encyclopedia Britannica's article on Achilles.