Dreadmoore

First of his name and first to commit unspeakable horrors during his tenure as a priest for the new church. In his hunt for immortality he has ended so many lives prematurely, that no one knows the number of his victims precisely. The worst of all, he has never faced justice as death has met him sooner. He serves as a prime example of where there is power, there will always be someone willing to abuse it to achieve what they want no matter the cost.
The priests and saints of the new church are meant to serve as examples to the rest of humanity. Their faith and sacrifices they went through their lifetimes in order to help others, fuel the magic power associated with devotion and miracles. They are meant to be better than the old gods of the past who had supposedly abandoned humanity and left them to fend for themselves, returning the prayers with nothing but an empty echo.
Dreadmoore, the Broken Saint, the Evil One is an unspoken secret that the new church does not want you to know about. It is a permanent dark stain on their pristine reputation. Still there are those who turn to him for help and he is the patron saint of many dark evil cults that may lurk in the shadows. Especially since he was able to get away with everything he has done with seemingly no bad consequences or downsides. It's the others, the weaker flock, the little lambs, that had to deal with all of the reprecussion that this entire affair brought to light.
The name itself Dreadmoore is not actually the name of the priest when he was alive and active - all mentions of him being purged from all publicly available archives. Dreadmoore comes from the fact that he used to dispose of the remains of his victims in a moor near the border of his parish.