Which Xbox game series stars Marcus Fenix as its central soldier?

Gears of War is the Xbox game series centered on Marcus Fenix.

Marcus is a former soldier of the Coalition of Ordered Governments who becomes the main playable character in the original Gears of War and its direct sequels. The series combines third-person shooting with cover-based movement, a design approach that became closely associated with the franchise.

Epic Games developed the first entries, beginning with Gears of War in 2006. Microsoft later acquired the franchise and transferred development responsibility to The Coalition, which produced Gears of War 4 and Gears 5.

Players sometimes confuse Marcus Fenix with John-117, the protagonist of Halo. Both characters are strongly associated with Xbox, but John-117 is the Master Chief, while Marcus belongs to the Gears universe and fights the Locust and other threats on the planet Sera.