Eighth Army may refer to:
Military units
- 8th Army (German Empire)
- 8th Army (RSFSR), a unit of the Red Army during the Russian Civil War
- 8th Army (Russian Empire)
- 8th Army (Soviet Union)
- 8th Army (Wehrmacht)
- 8th Guards Combined Arms Army, a unit of the Soviet Army
- 8th Guards Combined Arms Army (Russia)
- Eighth Area Army, a unit of the Imperial Japanese Army during World War II
- Eighth Army (France)
- Eighth Army (Italy)
- Eighth Army (Ottoman Empire)
- Eighth Army (United Kingdom)
- Eighth Army (United States)
- Eighth Route Army, a unit of the National Revolutionary Army during World War II
Other uses
- 8th Army (board game), a 1982 board wargame