Twelfth Army or 12th Army may refer to:
Germany 12th Army (German Empire), a unit in World War I 12th Army (Wehrmacht), a unit in World War II
Russia 12th Army (Russian Empire), a unit in World War I 12th Army (RSFSR), a Red Army unit in the Russian Civil War 12th Army (Soviet Union), a unit of the Soviet Army
Other countries Twelfth Army (Japan), a unit of the Imperial Japanese Army Twelfth Army (United Kingdom), a unit of the British Army Twelfth Army (Italy), a unit in World War I 12th Army (Austria-Hungary), a unit in World War I
See also XII Corps (disambiguation) 12th Division (disambiguation) 12th Wing (disambiguation) 12th Brigade (disambiguation) 12th Regiment (disambiguation) 12th Battalion (disambiguation) 12 Squadron (disambiguation)