Baron was an aristocratic title. The female form was Baroness.
Sir Stephan Palbury was the Baron of Fluxford on the planet Elbyon. (PROSE: The Sorcerer's Apprentice)
In Russia in 1908, Nicky Yusupov was killed in a duel with Baron Maneufel. (PROSE: The Wages of Sin)
Sherlock Holmes and the Seventh Doctor investigated Baron Maupertuis after the theft of Siger Holmes' journals from the Library of St John the Beheaded. (PROSE: All-Consuming Fire)
Baron Denton de Kay Leigh stole a therapy chair, then used it on the villagers of Armstrong's Colony, ingesting what was left after they had been placed in the chair and gaining their knowledge. (PROSE: The Heroine, the Hero and the Megalomaniac)