The Black Pope

The black pope is a mythical being linked to the dark underbelly of the superstitious rumours involving the Roman Catholic Church. Rumoured to be a sorcerer dabbling in dark arts, a warlock in service to an archfiend, or a necromancer, he or even she is meant to live somewhere in or under the city of Rome. Some rumours persist the Vatican knows who the person is and it's below the Vatican itself the black pope lives. Others claim that this being lives in the Holy Land, usually around Jerusalem, or Bethlehem, and even tied to Constantinople. Others postulate the black pope is the diametric opposite of the Pontiff, and has the powers of Hell & the Devil at their command, like an evil cleric.
Very few details are known for sure about the black pope, though some things have been verified over time. Firstly, there has been a good number of Tieflings as the black pope, and a small amount of chromatic Dragonborn. The hierarchy seems made up of a good few of these, as well as many humans. Their clothing is mainly dyed white for low level followers, purple and black for medium to high level members, and the black pope is usually in black coloured vestments. Amy trims or other adornments made of metal is made of silver. In quite a few instances the black pope and their hierarchy have been female.
The black pope & their followers have been having a covert war with the Christian religions for decades now. They sometimes back other major religions if it means Christianity loses, though this quickly turns sour & outright hostile when their erstwhile allies find out about the black pope and their backers, as well as their followers.