In the religion,folklore,and mythology of many cultures,demons are supernatural beings of great evil that hails from one of various realms of darkness. These places include Tartarus,Hell,and other more obscure dimensions. Their purpose in existence to tempt, torture and otherwise disrupt the lives of motrals.
The origins of demons vary. Some are fallen gods or angels, rejected from the heavens after becoming corrupt. Others may be creations of evil gods, or spawned from sin itself. They may be independent terrors, or may serve greater powers, such as stronger demons or Satan himself. Demons often crave some unsavory sustenance, such as blood, flesh ,or souls.
Dungeons and Dragons
Demons fall under three broad classifications. The most powerful are Elder Gods who turned to divine cannibalism for power and degenerated as a result. The second category consists of fallen gods from later generations- these are usually rulers of personal Hells. The third category includes unfathomable creatures from strange dimensions with bizarre goals.
DC (Post-Crisis, Post-Zero Hour)
Demons are arranged in various hierarchies, some of which paid fealty to Lucifer Morningstar and others elsewhere. Earth was once the domain of demons, until the first life emerged and somehow pushed them elsewhere.
Demons rule the underworld, the dimension for evil beings. They want to eradicate all good from the universe,from humans,to witches,to whitelighters. Demons can also be half-human and appear in human form. They come in Lower Level Demons and Upper Level Demons.
Demons dwell in Hell after Lucifer was banished from Heaven. Some demons were once angels and Muses before they were transformed as a result of following Lucifer or from choosing neither him or God in the war in Heaven. The first category seen are Golgothans, made entirely of human waste. Another category are red-furred monsters.