355th

355th may refer to:

Aviation

 * 355th Fighter Squadron, an inactive United States Air Force unit
 * 355th Fighter Wing, a United States Air Force unit assigned to the Air Combat Command's Twelfth Air Force
 * 355th Tactical Airlift Squadron, a U.S. Air Force squadron based at Rickenbacker Air National Guard Base
 * 355th Troop Carrier Squadron, an inactive United States Air Force unit
 * 355th Operations Group, a United States Air Force unit, assigned to the 355th Wing
 * 355th Aviation Company, of the United States Army
 * No. 355 Squadron RAF, WWII long range bombing squadron of the British Royal Air Force
 * 355th Reconnaissance Aviation Squadron, a Cold War era unit of the Yugoslav Air Force

Ground forces

 * 355th Infantry Regiment (United States), an infantry regiment of the United States Army
 * 355th Division (Imperial Japanese Army), a WWII home defence infantry division
 * 355th Infantry Regiment (Imperial Japanese Army), part of the 355th Division (Imperial Japanese Army)
 * 355th Rifle Division, a Soviet WWII infantry division