A viscount was a title of nobility on Earth, ranking above a baron and below an earl.
In 2369, Regina Bartholomew 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")