Demon

Demons, in Christian mythology, are the counterparts of angels. They are angels which have fallen from grace along with Satan. Demons are inherently evil and frequently plague humanity under the command of the devil.

Demonic possession

Demons are supposedly able to enter and take control of a human, this is called possession. The Catholic Church uses the ritual of exorcism to expel demons from the victims they possess.

Demon possession is also a historic explanation for those who suffer from neurological disorders such as epilepsy.