William Wildman Shute Barrington, 2nd Viscount Barrington, PC, was a British politician who sat in the House of Commons for 38 years from 1740 to 1778. He was best known for his two periods as Secretary at War during Britain's involvement in the Seven Years War and American War of Independence.

The Secretary at War was a political position in the English and later British government, with some responsibility over the administration and organization of the Army, but not over military policy. The Secretary at War ran the War Office. After 1794 it was occasionally a Cabinet-level position, although it was considered of subordinate rank to the Secretaries of State. The position was combined with that of Secretary of State for War in 1854 and abolished in 1863.