Daemon

To stay in this world a demon needs a body; animals and monsters are often used to that end.

Demons are being which are generally summoned into this world as spirit being that need to occupy a body in order to remain.

However it is possible for monsters to evolve into demons given that they are strong enough and have had enough time to evolve.

Demons are often referred to as Devils.

High Demon/Devil or Higher Demon/Devil refers to Greater Demons and Arch Demons.

Demon Dukes or Demon Noble's or Demon Officials refer to the aristocracy of Demons, which are all very powerful but still subdivided by strength.

The are ranked below from strongest to weakest.
 * 1) True Demon Lord
 * 2) Demon Lord
 * 3) Demon Duke
 * 4) Arch Demon
 * 5) Greater Demon
 * 6) Lesser Demon