M13, M-13 or M13 may refer to:
Military
- Fiat M13/40, an Italian tank used in World War II
- M13 Half-track, a U.S. anti-aircraft gun used in World War II
- M13 link, a machine gun's ammunition link
- M-13 rocket, a version of the Soviet World War II RS-82 rocket
- M13 revolver, a lightweight version of the Smith & Wesson Model 12 pistol for U.S. Air Force crew
Roads
- Highway M13 (Ukraine), an international highway connecting Ukraine and Moldova
- M-13 (Michigan highway), a state highway in the United States
- M13 (Cape Town), a metropolitan road near Cape Town, South Africa
- M13 (Durban), a metropolitan road in Durban, South Africa
Other uses
- M13, the Mathieu groupoid by John Horton Conway
- M13 bacteriophage, a virus that infects bacteria
- Magic 2013, the fourteenth core set in Magic: The Gathering
- Messier 13, a globular cluster in the constellation Hercules
- Miles M.13 Hobby, an airplane built by Miles Aircraft