William Julius "Judy" Johnson was an American professional third baseman and manager whose career in Negro league baseball spanned 17 seasons, from 1921 to 1937. Slight of build, Johnson never developed as a power threat but achieved his greatest success as a contact hitter and an intuitive defenseman. Johnson is regarded as one of the greatest third basemen of the Negro leagues. In 1975, he was elected into the Baseball Hall of Fame after being nominated by the Negro Leagues Committee.

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.