General Purpose Infantry Unit

The Grunt, formally known as the G.I.U. (General Infantry Unit) or Bipedal Robot, is a humanoid combat robot seen in Call of Duty: Black Ops III. Grunts are mass-produced robotic infantry in wide use by most major military forces and even by smaller factions, private corporations, and terrorist groups. Grunt armies are controlled by a distributed A.I. hivemind network, which typically prevents Cyber Core users from taking direct control of them, although their physical functions and even friend-or-foe indicators can still be hacked.

Although they fight with standard infantry weaponry, Grunts behave significantly differently from human soldiers, steadily walking forward into combat instead of attempting to utilize cover. Grunts do possess a degree of self-preservation programming and can dodge sideways several feet in an attempt to evade gunfire. They are typically equipped with assault rifles, shotguns, or submachine guns, and are generally not assigned sniper rifles or explosive weaponry. They also cannot utilize grenades.

Grunts are more durable than human troops due to their armored plating and mechanical nature, and are capable of surviving several bullet hits from most automatic weapons, although they can still be brought down with one or two high-caliber rounds or shotgun blasts. They are also significantly stronger than a human being, capable of easily ripping a human's limbs off their bodies or lifting a human by the throat off the ground using only one arm. However, cybernetically augmented Cyber Soldiers are strong enough to overpower them, and even skilled normal humans such as Rachel Kane can defeat a Grunt in melee combat by evading their attacks and using a firearm to target their weak spots.

In the missions Hypocenter, Lotus Towers, and Life, the local Grunt armies are taken control of by the Corvus A.I. through one of its hosts. Grunts under Corvus' direct control often behave in an atypical manner not consistent with their existing programming, often abandoning their weapons and charging forward directly at enemies, detonating themselves when they get close. Grunts controlled by Corvus are resistant to Cyber Core hacking or their higher functions such as their friend-or-foe indicator, although they are still vulnerable to abilities that target their physical functions, such as Immolate or Shutdown.