100th Heavy Anti-Aircraft Regiment, Royal Artillery, was a Scottish air defence unit of Britain's Territorial Army (TA) formed at Motherwell during the period of international tension leading up to the outbreak of World War II. It defended Glasgow during the early part of the war and then took part in the assault landings in Sicily (Operation Husky) and on mainland Italy (Operation Avalanche). The regiment continued in the postwar TA until amalgamated in 1950.