393rd or 393d may refer to:

• 393d Bomb Squadron (393 BS) is part of the 509th Bomb Wing at Whiteman Air Force Base, Missouri
• 393d Bombardment Group, inactive United States Air Force unit
• 393d Bombardment Squadron (Medium) (1942), inactive United States Air Force unit
• 393d 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 or 1st Hampshire Engineers, formed in 1862 responsible for the port defences of the South Coast of England
• 393rd Infantry Regiment (United States), U.S. Army Reserve regiment that is assigned to 75th Infantry Division (Training Support)

• 393 (number)
• 393, the year 393 (CCCXCIII) of the Julian calendar
• 393 BC
• All pages with titles beginning with 393d
• All pages with titles containing 393d