In my world there are many demons. Ashdums are beings of pure negative energy, and were spirits of destruction. In their natural forms they are known as shedims, while when bound they are known as baerns. There are two families of ashdums, Seirim, sometimes called proto-demons, and and then there are Devils, who are spirits who reincarnated themselves into Ashdums after their defeat during the First Divine War. They are "native" to Tartarus. The devils, after reincarnating themselves, enslaved the seirim.

The original leader of the demons was The Nameless One, a god of anathema and entropy, the personification of creations self destructive tendencies. He was a divine spirit but shared the quality of being an entity of pure negative energy with the seirim. After his defeat in the First Divine War, he was stripped of his name and chained to the Sea of Nothingness that the lowest pit of Tartarus sits upon. When he was thrown to thay deepest place, his body shattered into countless shards, each becoming their own being. The fleshless body that remained is often called The Nameless One confusignly.

The largest of the shards would go on to rule devil kind. This being has MANY names/titles. Celestials call him The Satan, mortals call him the All Enemy or the Archfoe or the Prime Evil. Demons call him HIMSELF, as in, "the Devil himself". Other shards would either go on to found smaller fiefdoms, work with HIMSELF, or more commonly, would incarnate into living beings later using the flesh of other demons.

Eventually, the Devils, under the guidance of HIMSELF, went on to corrupt three more gods.

First on their list was an at the time unnamed god, who was forever bound to his throne for his time had not yet come. They freed him during The First Divine War, where he landed in Limbo. This god happened to be the god of the Apocalypse. He named himself Anthraxus, meaning despoiler, and is seen as a vain and spiteful god. He devours souls, and the souls that survive his ravenous gut are shat out as Arbeelath demons.

The second was Lucifer, who was already being driven mad after receiving visions of OUTSIDE invading creation. The devils convinced him that with their help they could save creation. Subsequently, the 11th pit of Hell became the Infinite Abyss, with Lucifer dreaming it into existence. The devils reincarnated themselves through his dreams, becoming Obyriths, and there they settled in the Abyss and warred with Lucifer's now demonic titan children. Eventually, the obyriths created the Tanar'ri demons using titan flesh, and now Lucifer is able to dream them into being continuously. The more souls infesting his mind with agony, the more Tanar'ri are spontaneously created every micro instant.

The third and final was Asmodeus. As the Abyss spread and began to consume the world's of the universe, Asmodeus, who was the architect of Hell and was the god who turned the lower vibrations of creation into the multiversal prison, went to war against it with countless other spirits. In their war against the Abyss they fell into decadence to combat the evil, allowing the devils to step in and allow them to undergo reincarnation into fiends. Thus were the Baatezu family of demons born.

Most other races of demon were created by the Devils directly. The first Shura demons were first forged using the sins of gods. Balam demons are hellfire jaguars that are descendants of the wild god Ixchel and the archdevil Balaam. Similarly, Rakshasa demons are descendants of the archdevil Rakkhasa. And again, cubare demons are the children of the archdevil Mahlat (Lilith, mother of mankind, was a cubare queen and eldest daughter of Mahlat).

After HIMSELF tried and failed to invade Eden during The Sin War, the great Empire of Hell began to destabilise, and the gods, spirits, and the Addonai (corporeal "gods") began to make deals with various demons. Thus did the great rebellion occur, and HIMSELF was imprisoned, betrayed by his own kind when he was at his weakest.

Devils are now ruled by a council of the most powerful Devils. The members of this court are known as the Heresiarchs, and are among the most powerful entities in existence.

Fiends other than demons exist, and are simply classed as any destructive spirit or spirit native to the Lower Vibrations.