In military terms, 66th Division or 66th Infantry Division may refer to:
Infantry divisions 66th Infantry Division (Bangladesh) 66th Division (Imperial Japanese Army) 66th Infantry Division (Russian Empire) 66th Infantry Division (South Korea) 66th Guards Mechanized Division, Soviet Union 66th Guards Rifle Division, Soviet Union 66th Rifle Division, Soviet Union 66th Division (Spain) 66th Division (Syria) 66th Mechanized Infantry Division, Turkey 66th (2nd East Lancashire) Division, British Army, First World War 66th Infantry Division (United Kingdom), British Army, Second World War 66th Infantry Division (United States), United States Army
Cavalry divisions 66th Cavalry Division (United States), United States Army
Other divisions 66th Anti-Aircraft Artillery Division, Soviet Union
See also List of military divisions by number 66th Brigade (disambiguation) 66th Regiment (disambiguation)