SO1 may refer to: Specialist Protection Command a command division within the Specialist Operations Directorate of London's Metropolitan Police Service Special Operator: Naval Special Warfare, SEAL; see United States Navy SEALs#Special warfare ratings Sonarman First Class, a former American naval rank. A staff officer of the first class, usually an officer of commander, lieutenant colonel or wing commander rank. Special Operations 1 - Propaganda, of SOE (Special Operations Executive, British, World War II)