393rd or 393d may refer to:
393rd Bomb Squadron (393 BS) is part of the 509th Bomb Wing at Whiteman Air Force Base, Missouri 393rd Bombardment Group, inactive United States Air Force unit 393rd Bombardment Squadron (Medium) (1942), inactive United States Air Force unit 393rd Fighter Squadron or 179th Fighter Squadron, unit of the Minnesota Air National Guard 148th Fighter Wing located at Duluth Air National Guard Base, Minnesota 393rd (Hampshire) Heavy Anti-Aircraft Regiment, Royal Artillery 393rd Infantry Regiment (United States), U.S. Army Reserve regiment that is assigned to 75th Infantry Division (Training Support)
See also 393 (number) 393, the year 393 (CCCXCIII) of the Julian calendar 393 BC