Mark II or Mark 2 often refers to the second version of a product, frequently military hardware. "Mark", meaning "model" or "variant", can be abbreviated "Mk."

Mark II or Mark 2 may refer to:

Military and weaponry

• 16"/50 caliber Mark 2 gun, a U.S. Navy gun that was never mounted on any operational ship
• Vickers Medium Mark II, an interwar British tank
• Cruiser Mk II, a World War II British tank
• Mk 2 grenade, an American grenade used in World War II, Korean War and the Vietnam War
• Gerber Mark II (1967), an American double-edged combat knife
• Ruger MK II (1982–2005), an American semi-automatic pistol
• Ruger M77 Mark II, an American bolt-action rifle
• Thin Man nuclear bomb or Mark 2 nuclear bomb (1945), a gun-type plutonium bomb
• Mark II, a variant of the British Mark I tank
• Merkava Mark II, a variant of the Israeli Merkava battle tank
• Supermarine Spitfire Mk II, a Spitfire variant with a stronger Merlin engine

Vehicles

• British Rail Mark 2 (1964), a rail carriage design
• Jaguar Mark 2, an automobile produced from 1959 to 1967
• Continental Mark II (1956–1957), an American personal luxury car
• Ford Zephyr Mark II, an automobile produced in Australia and New Zealand
• Toyota Mark II, a series of Japanese car models
• Volkswagen Polo Mk2, an automobile produced between 1981 and 1994
• Bombardier ART Mark II, rolling stock used by Vancouver SkyTrain rapid transit

Other technologies

• Mark II (radio telescope), a radio telescope in England, constructed in 1964
• Harvard Mark II (1947), a computer built at Harvard University and used by the US Navy
• RCA Mark II Sound Synthesizer (1957), a musical instrument made of electronic components
• Canon EOS-1D Mark II, a digital SLR camera
• Canon EOS-1Ds Mark II, a digital SLR camera
• Canon EOS-5D Mark II, a digital SLR camera
• Dräger Oxy 3000/6000 MK II, Self Contained Self Rescuer (Mining)
• Mesa Boogie Mark II, a Mesa Boogie Mark Series electric guitar amplifier model
• Technics SL-1200, a direct-drive turntable very popular with DJ's
• Mariner Mark II, a proposed uncrewed spacecraft program
• SG-1000 II, also known as the Mark II, a redesigned version of the SG-1000 sold by Sega in 1984.

Other uses

• Mark 2 or Mark II, the second chapter of the Gospel of Mark in the New Testament of the Christian Bible
• Mark II of Alexandria, Patriarch of Alexandria in 141–152
• Pope Mark II of Alexandria, patriarch of the Coptic Church from 799 to 819
• Mark II of Constantinople, Ecumenical Patriarch in 1465–1466
• Mk II (album) a 1969 album by Steamhammer
• MK II (Masterplan album) (2007)
• MKII or Mortal Kombat II, a video game
• Gundam Mk-II, a robot of the fictional Gundam series
• Mark II (robot), a giant robot built by MegaBots Inc.
• Mark II (film), a 1986 New Zealand film
• Mark II line-up of rock band Deep Purple, the most celebrated line-up in the band's life span, with Ian Gillan, Ritchie Blackmore, Jon Lord, Roger Glover and Ian Paice
• The Guide Mark II from Mostly Harmless
• S/2015 (136472) 1, a moon of Makemake, nicknamed MK 2 by the discovery team.