M4

M4 or M-4 most often refers to:
 * M4 carbine, an American carbine
 * M4 Sherman, an American World War II medium tank

M4, M04, or M-4 may also refer to:

Arts and entertainment

 * M4 (EP), a 2006 EP by Faunts
 * M4 (video game), a 1992 computer game developed for the Macintosh
 * M.IV ("Matrix IV"), the fictional Warner Brothers videogame project inside the 2021 film The Matrix Resurrections

Weapons

 * Benelli M4 Super 90, an Italian semi-automatic shotgun
 * M4 cannon, an American 37 mm automatic gun
 * M4 Selectable Lightweight Attack Munition (SLAM), an American land mine
 * M4 SLBM, a French submarine-launched ballistic missile from 1985
 * M4 Survival Rifle, an American rifle in aircraft survival gear
 * Spectre M4, an Italian submachine gun
 * M4 bayonet, an American World War II bayonet used for the M1 Carbine
 * Gross-Basenach M IV, a pre-WWI German military semi-rigid airship

Aircraft, ships and vehicles

 * HSWMS Carlskrona, a 1980 Swedish Navy minelayer, later redesignated as ocean patrol vessel P04
 * HSWMS M4, a Swedish Navy mine sweeper
 * HMS Roberts (M4), a WWI British Royal Navy monitor
 * HMS M4, a British M-class submarine
 * M4 Tractor, a U.S. Army artillery tractor from 1943
 * Myasishchev M-4, a 1950s Soviet strategic bomber aircraft
 * Meusel M-IV, a German glider; see List of German gliders

Other uses in military

 * M4 flame fuel thickening compound, a substance used in fire bombs and incendiary weapons
 * M4 (German Navy 4-rotor Enigma), a variant of the Enigma cryptography machine
 * M04, desert variant of M05, a camouflage pattern used by the Finnish Defence Forces

Biology, medicine and organic chemistry

 * ATC code M04, Antigout preparations, a subgroup of the Anatomical Therapeutic Chemical Classification System
 * British NVC community M4, a type of mire plant community in the British National Vegetation Classification system
 * M4, the FAB classification of acute myelomonocytic leukemia
 * Muscarinic acetylcholine receptor M4, a protein

Computing and electronics

 * Apple M4, a central processing unit in the Apple M series
 * m4 (computer language), a macro processing language
 * M4, part number for a 1N400x general purpose diode
 * Sony Xperia M4 Aqua, a mobile phone
 * ARM Cortex-M, a processor family

Other uses in science and technology

 * Messier 4 (M4), a globular cluster in the Scorpius constellation of stars
 * Leica M4, a 1967 35 mm camera
 * M4, an ISO metric screw thread
 * Foton-M No.4, a Russian microgravity and bioscience research spacecraft launched in July 2014

Air

 * Covington Municipal Airport (Tennessee), FAA location identifier M04
 * Maule M-4, a 1960 American four-seat cabin monoplane aircraft
 * Miles M.4 Merlin, a 1930s British five-seat cabin monoplane aircraft

Rail

 * Bucharest Metro Line M4, Romania
 * Line 4 (Budapest Metro), Metro 4 or M4, Hungary
 * M4 (Copenhagen), a future expansion of the Copenhagen Metro, Denmark
 * M4 (Istanbul Metro), a subway line on the Asian side of Istanbul, Turkey
 * M4, variant of the M2, an American electric multiple unit on the Metro-North Railroad
 * M4, an American rapid transit car on the Market–Frankford Line
 * Milan Metro Line 4, rapid transit line in Milan, Italy
 * Sri Lanka Railways M4, a class of diesel-electric locomotive

Road

 * BMW M4, a car
 * M4 Vacamatic, a 1941 semi-automatic transmission made by Chrysler
 * M4, a bus route of Fifth and Madison Avenues Line, New York City, U.S.
 * Mid-engine, four-wheel-drive layout, or M4 layout, an automotive design
 * List of M4 roads

Other uses

 * Héctor David Delgado Santiago (1975–2013, alias El Metro 4, sometimes M4), deceased Mexican drug lord
 * M4, a measure of money supply
 * M4-, M4+ and M4x, disciplines in men's rowing
 * MLBB M4 World Championship, the fourth esports world championship for the mobile game Mobile Legends: Bang Bang held in 2023
 * M4, a difficulty grade in mixed climbing