Robert Joe Cox is an American former professional baseball third baseman and manager in Major League Baseball (MLB). Cox played for the New York Yankees and managed the Atlanta Braves and Toronto Blue Jays. He is a member of the National Baseball Hall of Fame. He recorded a 100-win season six times, a record matched only by Joe McCarthy.

A third baseman, abbreviated 3B, is the player in baseball or softball whose responsibility is to defend the area nearest to third base — the third of four bases a baserunner must touch in succession to score a run. In the scoring system used to record defensive plays, the third baseman is assigned the number 5.