M8
M8 or M-8 may refer to:

Computing, electronics, and engineering
 M8 (cipher), an encryption algorithm
 Leica M8, a digital rangefinder camera
 HTC One (M8), a smartphone
 Meizu M8, a smartphone
 M8, a standard bolt and nut size in the ISO metric screw thread system

Rockets
 M8 (rocket), an American World War II air-to-surface and surface-to-surface rocket
 M-8 rocket, a variant of the RS-82 rocket used by the Soviet Union in World War II

Transport

Civilian
 M8, a Paris Metro line
 M8 (New York City bus), a New York City Bus route in Manhattan
 M8 (railcar), a Metro-North Railroad car
 BMW M8, a sporty car from BMW 8 Series

Military
 M8 Armored Gun System, a US Army light tank cancelled in 1996
 M8 Grenade Launcher, see M7 grenade launcher
 M8 Greyhound, an American armored car used during World War II
 M8 Tractor, an artillery tractor used by the US Army
 Howitzer Motor Carriage M8, an American self-propelled howitzer vehicle developed during World War II
 Loening M-8, a 1910s American fighter monoplane 
 Miles M.8 Peregrine, a 1930s twin-engined light transport monoplane primarily used by the Royal Aircraft Establishment

Roads
 M-8 (Michigan highway), also known as the Davison Freeway
 M8 (Johannesburg), a metropolitan road near Johannesburg, South Africa 
 M8 (Port Elizabeth), a metropolitan road in Port Elizabeth, South Africa 
 M8 highway (Russia), also known as the Kholmogory Highway
 M8 motorway (Hungary)
 M8 motorway (Ireland)
 M-8 highway (Montenegro)
 M8 motorway (Pakistan)
 M8 motorway (Scotland)
 M8 Motorway (Sydney) in Sydney, Australia
 Highway M08 (Ukraine)
 Western Freeway (Victoria) in Australia, designated M8
 M8 Road (Zambia)

Other uses
 M8 Alliance, World Health Summit
 M8 (magazine), a dance music magazine based in Scotland
 Messier 8, also known as M8 or Lagoon Nebula, a giant interstellar cloud
 M8, Internet slang for "mate"

See also
 8M (disambiguation)