Cult of Orcus
The Cult of Orcus is a sect of people who worship the Abyssal Demon Lord Orcus.
There are different sects with different goals. Some pursue everlasting life and believe loyal service to Orcus will grant that to them. Others want to see society and all it's decadence brought down. Others are nihilists who believe that existence has no meaning and it's simply best bring about it's inevitable end.
What they all hold in common is their worship of Orcus as a means to accomplish their goals. They believe that unlike the gods who rarely show themselves and therefore must not care about their followers, Orcus lavishes his attention and gifts upon his faithful. The socially awkward carpenter who was mocked for his limp his whole life is now powerful and capable of bringing revenge on the people who tormented him with vengeful undead or pestilence.
Orcus commands his followers to sacrifice the living to please him. His followers make ritual sacrifice the centerpiece of any of their secret strongholds and go to great lengths to find sacrifices that will please Orcus. The Saint of a deity is the most sought after with traveling clerics known to disappear around regions infested by the cult.
The various sects of the cult operate independently to avoid detection. The leaders of the various sects know of each other but rarely communicate unless commanded to by Orcus or his servants. The cult will go to great lengths to conceal their identity and will threaten any possible turncoats with the prospect of not only themselves but their families becoming eternal undead servants to the cult as punishment.
There is rumored to be a gang of their followers looting tombs in Kordoth for unknown reasons.

Cult of Orcus
Purpose: Destroy Society, Eternal Life, Spread Undeath
Alignment: Chaotic Evil
Symbol: A Bull's Skull