|“|| Dante: The Bishop assured us that our sins would be absolved!|
Lucifer: And you believed him? You actually believed these salesmen of salvation?
|~ Lucifer, revealing to Dante Alighieri that the bishop lied to him about absolving his sins.|
Dark Priests are villains who are popular in many media. Despite the name, it is not required for such characters to be actual priests; any member of any clergy or cult is applicable for this category.
A Dark Priest uses his or her position to knowingly commit crimes that are deeply at odds with his religion. Often, they will try to convince themselves or others they are doing good but other times they may simply not care at all.
What makes a Dark Priest so dangerous is that, despite his/her obvious evil, he/she can still hold great power over others and, due to their status as a "man/woman of the cloth," he/she is often hard for a protagonist to counter without risking public backlash (especially if the setting is in the past, when the clergy had greater control than they do today). In many world religions, especially Christianity, a Dark Priest is also known as a False Teacher or False Prophet.
Alternatively, a Dark Priest may not actually be a member of the clergy at all, but a deranged and/or evil being who has adopted the guise of a cleric for whatever reasons they may have, or a corrupt and dishonorable clergyman who has renounced his divine allegiances to worship demons or, more simply, commit crimes.