To have once died but come back, revenants are also known as the Living Dead.
A revenant is born when a creature dies through an unjust manner. Murder, assassination, death penalty from a faulty or corrupted judge…the poor soul who was slain finds themselves awake, their soul still within their body which has been made anew, if somewhat scarred.
Due to the nature of their rebirth, a revenant is able to invoke the souls of ancient beings, masters of various forms of combat. Typically, a revenant will seek to end the people or person who killed them or had them slayed, but there is no penalty for this act never happening.
Because they wield dark magics of the soul but came back from an unjust death, people will react quite differently to revenants. Some understand that the revenant in question had no choice but to arise and live again, however the fact that they innately wield the powers of death and souls does not help them.