Viscount was an aristocratic title. The female form was Viscountess.
Viscount Gothard was the governor of the Darkheart colony. (PROSE: The Dark Path)
In 1970, a probe sent from Earth to Triton was picked up by the Waro. They were able to modify it and used it to telepathically contact Viscount Rose, directly sending their commands into his head. (PROSE: The Devil Goblins from Neptune)
While visiting 1580 Venice, the Eleventh Doctor used his psychic paper to convince an inspector that he and Amy Pond were a viscount and viscountess, and that Rory Williams was her eunuch. (TV: The Vampires of Venice)