Robert Stephen Ganley (April 23, 1875 – October 9, 1945) was an Irish-American professional baseball player who played as an outfielder in Major League Baseball from 1905 through 1909. He played for the Pittsburgh Pirates, Washington Senators and Philadelphia Athletics. In 572 games over five seasons, Ganley posted a .254 batting average (540-for-2129) with 246 runs, 2 home runs, 123 RBI, 112 stolen bases and 177 bases on balls.