403rd

403rd or 403d may refer to:


 * 403d Bombardment Squadron, inactive United States Air Force unit
 * 403d Operations Group, the operational flying component of the United States Air Force Reserve 403d Wing
 * 403d Wing, unit of the United States Air Force assigned to the Air Force Reserve Command
 * 403rd Infantry Brigade, known officially as the Peacemaker Brigade, one of the brigades of the Philippine Army