William Ignatius Nolan (May 14, 1874 – August 3, 1943) was a politician from the U.S. State of Minnesota.

He was member of the Minnesota House of Representatives from 1903 to 1907, 1911–1913, and 1917–1923, serving as speaker from 1919–1923.

Nolan was elected as a Republican to the 71st congress to fill the vacancy caused by the resignation of Walter Newton.

Nolan was reelected to the 72nd congress and served from June 17, 1929, to March 4, 1933.

He was elected State railroad and warehouse commissioner in 1942 and served until his death in Winona, Minnesota.