I read about it many years ago... and you would not believe where... a title from DC comics. Hehe. Those days, they would include some reference if they based a story line from something historical. In the comic book, they referred to the second Pope as the Black Pope.
But the 'Black Pope' is a nick name, in a manner of a joke, they gave to Secretary General of the Jesuits (Society of Jesus), since he is always dressed in black.