Dark Priests or Dark Priestesses are popular villains; despite the names they are not required to be actual priests, as religious members of a clergy or Cult are applicable. They can also be people who use the word of God/Goddess (whatever they worship and however many there are in their religion) to justify their actions.

They use their positions to knowingly commit crimes at odds with their religions but convince themselves and/or others they are good or do not care. What makes them dangerous is that despite their obvious evils they can still hold power and due to their status they are hard to counter without backlash, especially when clergy members have greater control in a setting. In real-world religions, especially Christianity they are known as false preachers, false teachers and false prophets.

Alternatively, they may not actually be part of a Clergy but deranged and/or evil beings adopting the guise of a cleric or corrupt and dishonorable clergy members who renounce divine allegiances to worship otherwise and/or commit crimes.