* The hero's loss. The hero may have lost a loved one to violence or illness, and they are driven by a desire for revenge or justice.
* The hero's quest. The hero may be on a quest to find a magical artifact or defeat a powerful enemy.
* The hero's redemption. The hero may have made a mistake in the past, but they are given a chance to redeem themselves.
* The hero's transformation. The hero may start out as an ordinary person, but they are transformed into a powerful being by some event or experience.
These are just a few examples of the many different types of back stories that can be used to create a compelling character.