Mason Alan Dinehart (born April 30, 1936), also known as Mason Alan Dinehart III, Alan Dinehart III, or Mase Dinehart, is an American business consultant and retired actor best known for his role as a youthful Bat Masterson in thirty-four episodes between 1955 and 1959 of the ABC/Desilu television series The Life and Legend of Wyatt Earp, starring Hugh O'Brian in the title role of the frontier marshal Wyatt Earp.