Sixth Army may refer to:
Germany 6th Army (German Empire), a World War I field Army 6th Army (Wehrmacht), a World War II field army 6th Panzer Army
Russia 6th Army (Russian Empire) 6th Army (RSFSR) 6th Army (Soviet Union)
Others Sixth Army (France) Sixth Army (Italy) Sixth Army (Austria-Hungary) Sixth Army (Ottoman Empire) Sixth Army (Japan) Sixth United States Army