Robert Henry Mavis (April 8, 1918 – March 1, 2005) was an American professional baseball player, manager and scout. Although he fashioned a long and successful playing career in minor league baseball as a second baseman and third baseman, his Major League career consisted of a single game. In the closing days of the 1949 season, on September 17, Mavis pinch-ran for Detroit Tigers catcher Bob Swift in the ninth inning of a game against the New York Yankees. He got as far as second base, but the game ended on a double play and he did not score a run. He was never called upon again that season, and in 1950 he resumed his minor-league career.