84th Regiment or 84th Infantry Regiment may refer to: * 84th Regiment of Foot (1759), a unit of the British Army, active from 1759 to 1765, which served entirely in British India * 84th Regiment of Foot (Royal Highland Emigrants), a unit of the British Army, active from 1775 to 1784, which served in the American Revolutionary War * 84th (York and Lancaster) Regiment of Foot, a unit of the British Army, active from 1793 to 1881, which served in the Napoleonic Wars and in India * , a unit of the Philippine Commonwealth Army, active from 1942 to 1946, which served in the Second World WarAmerican Civil War * 84th Illinois Volunteer Infantry Regiment, a unit of the Union (North) Army * 84th Regiment Indiana Infantry, a unit of the Union (North) Army * 84th New York Volunteer Infantry Reg