William McKee Dunn (December 12, 1814 – July 24, 1887) was a U.S. Representative from Indiana and the Judge Advocate General of the United States Army.

During the early part of the American Civil War, in addition to his congressional duties, Dunn served in the Union Army as a volunteer aide-de-camp to General George B. McClellan from June 19, 1861, to August 1861, in the campaign in western Virginia.

Following his unsuccessful bid to remain in Congress, Dunn accepted a military commission from the Governor of Indiana, fellow Republican Oliver P. Morton.

He was appointed lieutenant colonel and Assistant Judge Advocate General of the United States Army on June 22, 1864.

He was interred in Oak Hill Cemetery, Washington, D.C.[4] This article incorporates public domain material from the Biographical Directory of the United States Congress