Ninja Gaiden is an action-adventure game developed by Team Ninja for the Xbox video game console. It went through five years of development before its release by Tecmo in 2004, and had a number of expansion packs and two remakes, Ninja Gaiden Black and Ninja Gaiden Sigma. The game follows the fictional story of Ryu Hayabusa, a master ninja, in his quest to recover a stolen sword and avenge the slaughter of his clan.

Tecmo specifically targeted Ninja Gaiden at a non-Japanese audience, and despite difficulties in obtaining content ratings due to the game's graphic depictions of violence, it was generally well received, and 362,441 copies were sold in North America in the first month after its release. Nevertheless, the game had to be censored for release in some regions, and Japanese sales were poor, with only 60,000 in the four months following its release. Making use of the Xbox's internet connectivity, Ninja Gaiden was the focus of a series of online contests across North America, Europe and Japan. Record-breaking numbers of players took part, competing for places in the live final, which was held during the Tokyo Game Show (TGS) 2004.

Team Ninja continued to update the game after its release: two Hurricane Packs were made available as free downloadable content that added extra content, gameplay challenges, and game engine improvements. These were incorporated into reworked version, released in 2005 and entitled Ninja Gaiden Black, that was regarded by the game's creator Tomonobu Itagaki and many players as the definitive version. In 2007, Ninja Gaiden was graphically enhanced on the PlayStation 3, with extra content, in the form of Ninja Gaiden Sigma. This version was later released on the PlayStation Vita as Ninja Gaiden Sigma Plus.