William J. "Bill" Warner (January 24, 1881 – February 2, 1944) was an American football player and coach. Warner graduated from Cornell University in 1903 and was a member of the Sphinx Head Society. He was elected to the College Football Hall of Fame in 1971.
Following his playing career at Cornell University, Warner was the head football coach at Cornell University, the University of North Carolina, Colgate University, St. Louis University, and the University of Oregon.
Warner was the brother of famed football coach Glenn Scobey Warner. In 1902, Bill and Glenn both played pro football for the Syracuse Athletic Club during the first World Series of Football, held at Madison Square Garden. It was during this event, that Warner played in the very first professional indoor football game as his Syracuse squad upset the heavily favored "New York" team. While Glenn was injured during the event with a head injury, Bill and the rest of the Syracuse team went on to win the event.