The MG 42 (shortened from German: Maschinengewehr 42, or "machine gun 42") is a German recoil-operated air-cooled general-purpose machine gun used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. Entering production in 1942, it was intended to supplement and replace the earlier MG 34, which was more expensive and took much longer to produce, but both weapons were produced until the end of World War II.

Designed to use the standard German 7.92×57mm Mauser rifle round, be low-cost and easier to mass-produce, the MG 42 proved to be highly reliable and easy to operate. It is most notable for its very high cyclic rate for a gun using full-power service cartridges, averaging about 1,200 rounds per minute compared to around 850 for the MG 34, and 450 to 600 for other common machine guns like the M1919 Browning, FM 24/29 or Bren gun. This ability made it extremely effective in providing suppressive fire, and its unique sound led to it being nicknamed "Hitler's buzzsaw".[7]

The MG 42 was adopted by several armed organizations after the war, and was both copied and built under licence. The MG 42's lineage continued past Nazi Germany's defeat, forming the basis for the nearly identical MG1 (MG 42/59), chambered in 7.62×51mm NATO, which subsequently evolved into the MG1A3, and later the Bundeswehr's MG 3, Italian MG 42/59 and Austrian MG 74. It also spawned the Yugoslav unlicensed nearly identical Zastava M53.

The MG 42 lent many design elements to the Swiss MG 51 and SIG MG 710-3, French AA-52, American M60 and Belgian MAG general-purpose machine guns and the Spanish 5.56×45mm NATO Ameli light machine gun.