Orcus
Orcus is a Lord of the Abyss, whose dominion over undeath has earned him the epithet the God-Lich. He was once a demon, born of the chaos of the Abyss, but has lived longer than some gods and has risen to a commensurate level of power, and at some point he became what is usually thought to be impossible - an undead demon. While not widely worshipped by the mortals of Ahren, he nevertheless has followers among morally flexible mages, especially necromancers driving toward becoming liches themselves. However, to serve Orcus is a dangerous bargain, and one must give up more and more of themselves and their free will in order to stay in his favour.
A chaotic evil diety, his symbol is a demonic skull picked clean of its flesh. Divine spellcasters inspired by the God-Lich gain access to the Chaos, Evil, Death and Void domains. His sacred weapon, unsurprisingly, is a scythe.
History
Orcus's origins are shrouded in the mystery of time and the volatility of his native realm, the Abyss. Orcus is a Lord of the Abyss whose domain is expansive, and while his cult is extensive and he is generous with his gifts to his followers, the nature of his cults tends to attract opposition from more organized faiths quickly, making large and historic campaigns of his influence impossible. In point of fact, his followers on Ahren tend to be jealous of their lore and are mistrusting of even each other.
Relationships
All of the Lords of the Abyss war with each other constantly, shifting alliances amongst each other in like manner to how mortals shift their clothes. His domain puts him near Zura and the pair frequently war against each other, uniting only when threatened from the outside, owing to their differing views of the purposes of undeath.
Appearance
Orcus maintains no illusions, and appears before mortals in the form of an enormous, skeletal, winged demon of the Abyss, whose ribecage is filled with softly-glowing red mist.
Realm
Orcus is master of the Carrion Fields, an enormous expanse full of damned souls doomed to serve him as ghouls, skeletons, and zombies.
Providence
Abraxas is the king of the spoken geas, the master of the incantations of banishment, and the father of languages. His faithful have seen his intervention in the form of the shuffle, the sudden landing on a particular page, or the gibberish that gets stuck in the back of one's mind, just under their tongue.
Servants
Many species of demon pledge their loyalty to Lords of the Abyss, among whom Orcus is no exception. While Dretches are, as always, over-represented, he is also popular among the Vergarra.
Church
One can hardly call the followers of Orcus a church. Occasionally, a cell of cultists may grow no larger than a half-dozen members in size. Much more often, individual spellcasters, or perhaps a spellcaster and one or two overly-trusting apprentices, may find themselves working together in the service of the God-Lich.
Worshippers
Mortal worship of Orcus is not altogether uncommon. Some spellcasting necromancers - in particular those who wish to obtain Lichdom or Godhood for themselves - will occasionally fall under the sway of Orcus, giving up more and more of their free will as they are tangled deeper and deeper into his web.
Clergy
A rare few of Orcus's followers, walk down the twisted roads of knowledge and lore far enough that they come into direct contact with him or his abyssal lieutenants, and so form pacts that make them formal members of his clergy while still maintaining some of their free will. Warlocks and Clerics in particular are over-represented in this cohort. Most are dedicated necromancers, serving as proxies for Orcus over their own hordes of mindless undead, and it's from this class of his followers that Liches are most likely to spring.
Temples & Shrines
Raising permanent temples to Abraxas is an extremely dangerous game. Worshipping Orcus openly, especially together with necromantic exercises, is punishable by death in essentially every territory of Wisteria.
Holy Texts
The Lords of the Abyss consider nothing sacred. No word, much less a facsimile of their word, may be used to bind them. Their only teachings are that which they or their lieutenants or priest pass along to the next generation, and their only law is their current demand.
Church History
Orcus's church has never been organized enough to be a meaningful historical force.