William Babcock Hazen (September 27, 1830 – January 16, 1887) was a career U.S. Army officer who served in the Indian Wars, as a Union general in the American Civil War, and as Chief Signal Officer of the U.S. Army. His most famous service was defending "Hell's Half Acre" at the Battle of Stones River in 1862.

Civil War
As the U.S. Army was drawn down following the war, Hazen was redesignated as colonel of the 38th U.S. Infantry in July 1866 and transferred to the 6th U.S. Infantry in March 1869. He served primarily on the Western frontier, but also visited Europe as an observer during the Franco-Prussian War. He offered testimony in one of the procurement corruption scandals that rocked the administration of President Ulysses S. Grant, which resulted in the resignation of Grant's Secretary of War, William W. Belknap.
On December 15, 1880, President Rutherford B. Hayes promoted Hazen to brigadier general and appointed him Chief Signal Officer of the U.S. Army, a post he held until his death. One of the duties of the U.S. Army Signal Corps at the time was the management of the Weather Service and Hazen came under indirect criticism for the government's lack of response to the distress of the 1881 Alaska expedition under Lieutenant Adolphus Greely.
Hazen married Mildred McLean, daughter of Washington McLean, the owner of The Washington Post.
Hazen died in Washington, D.C., and is buried in Arlington National Cemetery. Hazen Bay in Alaska is named in his honor.