Fifth Army may refer to:
Germany 5th Army (German Empire), a World War I field Army 5th Army (Wehrmacht), a World War II field army 5th Panzer Army 5th Army (GDR), a Warsaw Pact field army in the Cold War to be activated in case of a war with NATO
Russia/USSR 5th Army (Russian Empire) 5th Army (RSFSR) 5th Army (Soviet Union) 5th Combined Arms Army (Russian Federation)
Others 5th Army (Austria-Hungary) Fifth Army (Bulgaria) Fifth Army (Nationalist China), see 88th Division (National Revolutionary Army) Fifth Army (France) Fifth Army (Japan) Fifth Army (Ottoman Empire) Fifth Army (United Kingdom) Fifth United States Army Fifth Army (Italy) 5th Army (Kingdom of Yugoslavia) Special Frontier Force of India, during the Indo-Pakistani War of 1971