Operation Bittern (Norwegian: Bittern-ekspedisjonen, known as Bitern in the oldest sources) was a military operation in occupied Norway planned and carried out in 1942 by the British Special Operations Executive (SOE) and the Norwegian government-in-exile in London.

Four SOE agents and instructors—Thor Helliessen, Jan Allan, Ruben Langmo and Johannes S. Andersen—were sent to Norway and parachuted into Nordmarka north of Oslo in October 1942.