The Game Boy is a compact video game system developed and manufactured by Nintendo, released in 1989 at US$89.95. The Game Boy was the first successful handheld console, and was the predecessor of all other iterations of the Game Boy line.

The Game Boy was originally bundled with the puzzle game Tetris.

As of March 31, 2005, the Game Boy and Game Boy Color combined have sold 118.69 million units worldwide. The Game Boy line has become the quintessential handheld gaming system, and until the recent Nintendo DS, was by far the most popular one on the market.

At the time of its release in 1989, the Atari Lynx was also just being introduced to the market. This system featured color graphics, a backlit screen, and networking capabilities. Nevertheless, its release price of $179, substantial requirement of 6 AA batteries that would provide roughly only four hours of gameplay (compared to 35 hours on 4 AA batteries for the Game Boy), physical bulkiness, and other factors doomed it to a second-rate status.

In 1991, Nintendo experienced heavier competition from Sega's Game Gear. To promote its new, color console, Sega aired a number of negative but unsuccessful ad campaigns in the United States that criticized the Game Boy's monochrome color palette. Like the Lynx, it too required six AA batteries that only lasted about 4-6 hours and was much more expensive than the Game Boy. The Game Gear had the advantage of being fully compatible (with an adapter) with all Sega Master System games and, while not as successful as the Game Boy, it sold from 1991 until early 1997.

One of the top-selling games for the Game Boy was Tetris, which sold about 30 million copies in the US, and is an example of a killer app. Tetris was packaged with the Game Boy and, often, consumers were buying the Game Boy to play Tetris.

The last game released and marketed for the original Game Boy was Pokémon Yellow in 1999, although numerous games released over the next few years for its successor, the Game Boy Color, would also be playable on the system. The last game released for the GameBoy Color which is also compatible with the original GameBoy was From TV Animation - One Piece: Maboroshi no Grand Line Boukenki!, released in June 2002 in Japan.