Joshua "Josh" Gibson, catcher in baseball's Negro Leagues. He also played for the Dominican League, the Mexican League & served as the 1st manager of the Santurce Crabbers, one of the most historic franchises of the Puerto Rico League. He was considered one of the very best catchers & power hitters in the history of ANY league, including the MLB. Known as the "Black Babe Ruth," some fans called Ruth the white Josh Gibson. He never played in MLB; it excluded non-whites during his lifetime.
Buck O'Neil was the first African American coach in Major League Baseball. Before that he played first base and coached for the Kansas City Monarchs of the Negro Leagues. He was an incredible man and the best ambassador baseball ever had.