Marquis de Sade

The Marquis de Sade, better known as Prisoner 6 or Monsieur le 6, was a French nobleman imprisoned in the Vincennes prison. In the summer of 1783, he began work on the book The 120 Days of Sodom. (PROSE: The Adventuress of Henrietta Street) River Song claimed to have escaped from his private boudoir. (AUDIO: The Sonomancer)

In an alternate Paris, the Marquis de Sade was imprisoned in the Bastille in 1804. He could not remember who he was. (PROSE: The Man in the Velvet Mask)