504th

504th may refer to:


 * 504th Battlefield Surveillance Brigade (BfSB), located at Fort Hood, Texas
 * 504th Bombardment Group (504th BG), a World War II United States Army Air Forces combat organization
 * 504th Expeditionary Air Support Operations Group, active United States Air Force unit
 * 504th Fighter Squadron or 137th Airlift Squadron flies the C-5 Galaxy and the C-17A Globemaster III
 * 504th Infantry Regiment (United States) (504th PIR) is an airborne infantry regiment in the United States Army