81st Brigade

81st Brigade may refer to:


 * 81st Mechanized Brigade (Romania), a unit of the Romanian Army
 * 81st Mixed Brigade, a unit of the Spanish Republican Army
 * 81st Brigade (United Kingdom), a formation of the British Army in the First World War
 * 81st Armored Brigade Combat Team (United States), a unit of the United States Army
 * 81st Airmobile Brigade (Ukraine), a unit of the Ukrainian Air Assault Forces