Agents of death are made of all races and genders. They are in the "employment" of Death. Who after realizing that there are to many people in the world for him to deal with, created the agents.
Becoming an Agents is not something many want. To become one, one must have done great evil on to others. These people are offered a way to redeem them self from all the bad they have done. They are to roam the world forever and collect the souls of the dead and dying. Failing to take a soul could get they banished to the dark age.
When it comes to appearance, all look different. But they all share some characteristics. Most notably are their black cloaks and hoods. With their face being invincible due to their face being a black void.