In a documentary on the BBC about Édouard Manet a link was made between his painting Olympia and Olimpia Maidalchini, Pope Innocent X's sister-in-law. She was sometimes referred to as "la papessa" and certainly seems to have been the power behind the Pontifical Throne.
According to papal historian Ludwig von Pastor, "the misfortune of Pope Pamphilj was that the only person in his family who would have had the qualities necessary to fill such a position was a woman."
There doesn't seem to be any real (or even marginally credible) evidence that she was also his mistress, but the accusation was - rather obviously - levelled at her. Apparently this was what made Manet's painting so racy: the name and the connection with an infamous courtesan.
Innocent X was painted by Diego Velázquez, whose portrait was the inspiration for Francis Bacon's "Screaming Pope" above. I don't know why that painting fascinates me. It just does. And seeing the two of them together is quite interesting.
At least I think so.