William J. Madigan
- Bats Unknown, Throws Right
- Weight 126 lb.
- Debut July 10, 1886
- Final Game September 4, 1886
- Born July 18, 1868 in Washington, DC USA
- Died December 4, 1954 in Washington, DC USA
William Madigan made his major league debut before he turned 18. In his one major league season, with the Washington Nationals in 1886, he went 1-13 for a team that went 28-92. He was the youngest player in the league.
The following year he played for Binghamton.