409th

409th may refer to:


 * 409th Air Expeditionary Operations Group, provisional United States Air Force unit assigned to Air Mobility Command
 * 409th Bombardment Squadron or 909th Air Refueling Squadron (909 ARS), part of the 18th Wing at Kadena Air Base, Japan
 * 409th Fighter Squadron or 194th Fighter Squadron, aviation unit of the California Air National Guard
 * 409th Support Brigade (United States), support brigade of the United States Army