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

William Ignatius Nolan
Member of the U.S. House of Representatives from Minnesota's 5th district
In office July 17, 1929 – March 3, 1933
Preceded by	Walter Newton
Succeeded by	Theodore Christianson
24th Lieutenant Governor of Minnesota
In office January 6, 1925 – June 1929
Governor	Theodore Christianson
Preceded by	Louis L. Collins
Succeeded by	Charles Edward Adams
34th Speaker of the Minnesota House of Representatives
In office 1919–1925
Preceded by	Ralph J. Parker
Succeeded by	John A. Johnson
Member of the Minnesota House of Representatives
In office 1903-1907 1911-1913 1917-1923
Personal details
Born	(1874-05-14)May 14, 1874 Saint Paul, Minnesota, U.S.
Died	August 3, 1943(1943-08-03) (aged 69) Winona, Minnesota, U.S.
Political party	Republican
Spouse	Matea E. Solem ​ (m. 1894)​
Profession	lecturer, politician

Nolan was born in Saint Paul, Minnesota and served in the Minnesota National Guard from 1891 to 1896.

He was member of the Minnesota House of Representatives from 1903 to 1907, 1911–1913, and 1917–1923, serving as speaker from 1919–1923. He was Lieutenant Governor of Minnesota from 1925–1929. Nolan was the chairman of the Minnesota Reforestation Commission in 1927.

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 an unsuccessful candidate for reelection in 1932 to the 73rd congress and continued to be an unsuccessful candidate for nomination in 1934, 1936, and 1938. Nolan resumed his profession as a lecturer. He was elected State railroad and warehouse commissioner in 1942 and served until his death in Winona, Minnesota.