Grunts are the most common enemy in the Army of Two series, appearing in every level. They are inaccurate, cowardly, and are easily killed. They pose the greatest threat when they attack in large numbers. There are different types of Grunt in each level in Army of Two, such as Afghan Grunts and United States Army Grunts.

Lightly armored, Grunts usually fall after taking a few hits. At least three quarters of the enemies encountered on each level are Grunts. The grunts also have an icon over their heads with one stripe, possibly showing their lowly status through the army rank of 'Private.'

In Army of Two: The 40th Day, all Grunts are mercenary privates. They carry G36Cs, SCAR-Ls, M4s, RPG-7s, and may have helmets.

The 40th Day Grunts normally wear ski masks and, strangely, surgical masks.