These guys are by far the most common Covenant enemy you'll face. At best, they're a bit of welcome comic relief and quiet carnage therapy; at worst, they're a vicious, nasty swarm of little beasts that can flood you and not only kill you, but make you embarrassed to be dead. Cowardly and annoying are the best descriptions of Grunts. They're almost always accompanied by an Elite, and will run away if he's killed, so aim for the tall guy. And watch for grenades, which can make even Grunts occasionally dangerous.