Benedict IX

Benedict IX was a pope in the 11th century who founded the Haereticum. She had a relationship of familiarity with the Doctor, knowing that he lived a life of regret. The Twelfth Doctor remembered her as a "bad girl". "Lovely girl, what a night!" he recalled, "I knew she was trouble, but she wove a spell with her castanets." Benedict made a personal recommendation for the Doctor's aid, in writing, in 1045. She once offered the Doctor a chance at confession, feeling that he was "more in need of confession than any man breathing", but the Doctor replied "it would take too much time".

A painting of her guarded the entrance to her library of heresies, into the 21st century. (TV: Extremis)

Behind the scenes
In the real world, Pope Benedict IX was a man, though not without his scandals.