The term grunt is slang for an infantryman in the U.S. military and some of the other armed forces of the English speaking world, and both Army and Marine infantrymen are known to take extreme pride in the term. It was used especially in the Vietnam War: "They were called grunts. They were the infantrymen, the foot soldiers of the war" (Bernard Edelman).
The term "grunt" may have come from observing heavily laden infantrymen make grunting sounds as they footmarched.
In the game Battalion Wars, grunts are low class troopers who may be a bit weak as indiveduals, but they are all powerful in big numbers. They look like kids and act like kids. They have funny voices. They run in a silly manner, and when they jump, their backpacks flop up and down. They are equipped with fully automatic M17 assault rifles.
Grunt is a bot in Quake III Arena. Grunt uses weapons the way a soldier should use them — the right tool for the job. When in a short range game, he will use the shotgun if he has it. When there is some distance between him and his opponent, he will use his rocket launcher. He moves quickly around the map, preferring to jump when it gets him someplace faster.
In the .hack// series of games it is possible to raise, race and ride cow-like creatures called Grunties (in the English version). They also feature in the spinoff anime and manga series.
In the Warcraft series of games Grunts are the basic Orcish foot soldiers. They are depicted as large, axe-wielding orcs with a wooden shield and patched armor.