Major General William George Haan (October 4, 1863 – October 26, 1924) was a senior United States Army officer who commanded the 32nd Division in World War I.
He graduated from the United States Military Academy in 1889, from the U.S.
Army War College in 1905, and was commissioned into the Field Artillery Branch.
He served in Cuba and the Philippines, and in 1903 went to Panama at the request of Theodore Roosevelt.
He was Acting Chief of Staff of the Pacific Division during the Army's relief work following the 1906 San Francisco earthquake.