William Wallace Brown (April 22, 1836 – November 4, 1926) was a Republican member of the U.S. House of Representatives from Pennsylvania.

He enlisted in the Twenty-third New York Volunteers in 1861, and transferred to the First Pennsylvania Rifles on December 18, 1861.

Brown was appointed recorder of deeds of McKean County, Pennsylvania, in 1864 and its superintendent of schools in 1866.

He was appointed aide-de-camp to Governor John F. Hartranft in 1876 and was associated with the Pennsylvania National Guard.

He was appointed Assistant Attorney General by President Theodore Roosevelt in 1907, and served until 1910.