Marquis de Sade
Donatien Alphonse François, Marquis de Sade (1740-1814) was an infamous French aristocrat and author. The mental disorder known as Sadism, whose sufferers derive pleasure from the pain of others, is named after him.
His most notorious book, The 120 Days of Sodom was written by de Sade whilst he was imprisoned in the Bastille. The last years of his life were spent in a lunatic asylum, though this may have been to avoid his mother-in-law, who, scandalised by his behaviour, had obtained a royal order for his arrest and indefinite detention; this has been dramatised in the play Marat/Sade.
His works are obscene to a degree that was unparalleled in modern literature until the relaxation of obscenity laws which occurred during the sexual revolution of the 1950s and 1960s. Books by Pauline Reage and Anne Rice reintroduced sadism-themed pornography to the literary world with the cachet that smut can be well-written, literate and as innocent as Disneyland.