Madame de Pompadour

Fact- Madame de Pompadour is one of the most infamous royal mistresses. She was the official royal mistress to French Louis XV for almost 20 years. She is thought to have had a STI that made sexual relations painful. However, by keeping Louis entertained outside the bedroom, she kept her place at court and in his favor until her death.

http://en.wikipedia.org/wiki/File:Boucher_Marquise_de_Pompadour_1756.jpg