A viscount was a title of nobility on Earth, ranking above a baron.
In 2369, Regina Barthalomew told Jean-Luc Picard that he reminded her of Viscount Oglethorpe. (TNG: "Ship In A Bottle")
Henry Burleigh, a character in the holonovel Janeway Lambda One was "Viscount Timmons". (VOY: "Learning Curve")