Metal Gear (commonly abbreviated to MG) is a stealth game designed by Hideo Kojima. Metal Gear was developed and first published by Konami in 1987 for the MSX2 home computer. It was well-received critically and publicly, scoring 91% in GameSpot's aggregate.

The game's premise revolves around a special forces operative codenamed Solid Snake who goes into a one-man sneaking mission into the hostile nation of Outer Heaven to destroy the Metal Gear, a bipedal walking tank capable of launching nuclear missiles from anywhere in the world. Most of the subsequent games in the series follow this same premise, often changing the characters, locations, and weapons.

Originally released for the MSX2 in Japan and Europe, the game was later ported to the Nintendo Entertainment System during the same year, although with many significant changes made to the game. This was followed with ports to various home computers, such as the IBM PC and Commodore 64. It was also ported to mobile phones in 2004 and for the PlayStation 2 in 2005 (as a component of Metal Gear Solid 3: Subsistence), with several enhancements and changes, such as typo corrections and some grammatical changes.

Its success led to the creation of two separately-produced sequels; the first one (Snake's Revenge) was produced specifically for the Western market for the NES and the other (Metal Gear 2: Solid Snake) was the canonical sequel developed by the original game's designer and released in Japan for the MSX2 in response to the former's creation. The latter was followed by a successful series of sequels and spinoffs.