91st Heavy Anti-Aircraft Regiment, Royal Artillery (91st HAA Rgt) was a part-time unit of Britain's Territorial Army (TA) formed in the West Riding of Yorkshire just before the outbreak of World War II. Its service during the war included Home Defence during the Battle of Britain and The Blitz, and a length period in Middle East Forces. Postwar it continued to serve in the TA in the air defence role until 1955.