Demons are evil creatures with powers that try to kill the Charmed Ones. They do not have souls so therefore can kill innocent people with contious. Most demons work for "The Source" but some hate him. The Source of all Evil is a very powerful demon who rules the Underworld. The Charmed ones have killed The Source three times. There are different ranks of demons and the Charmed ones have faced them all. In some situation demons actually helped the Charmed ones. Demons try to kill the Charmed ones to impress the Source and all of the Underworld.