Dark One

The power created to protect the dead and escort them to their final destination. At some point he left his role and rebelled. His power created the undead and has the ability to control them. He fought the Lady in the Forest and they both fell in that battle. Neither was able to truly slay the other.
When he rebelled the Creator had Ezra the Enchanter create a scythe holding the power of the Dark One, the wielder could either merge with the Dark One or replace him.