Unggoy

The basic infantry unit of the Covenant, Grunts are the lowest beings in the Covenant hierarchy. They present little threat individually, but are dangerous in large numbers. Grunts, known as Unggoy (which means "monkey" in Tagalog[citation needed]) in the Covenant language, are the workhorses of the Covenant. They serve as common laborers across Covenant controlled space. Short, stocky, and relatively slow, they will often panic when faced with superior forces. However, if they are being led by an Elite, they will stand and fight. It should be noted, that Heretic Grunts do not show fear and continually attack the player, even if the lead Elite dies. Despite their obvious cowardice, they are extremely large in numbers and breed rapidly, and - when cornered - can attack with suicidal desperation. Grunts are usually armed with single handed weapons, like plasma pistols, needlers, and plasma grenades (which they are incredibly good at aiming), although the Arbiter can give his Grunt allies a Plasma Rifle and Brute Plasma Rifle, even though they never typically use one.

Their homeworld is a frozen, swampy planet with a methane atmosphere and naturally occurring pillars of fire. Because they breathe methane they are forced to rely on a large, bulky SCUBA-like "rebreather" system in order to survive in oxygen atmosphere areas - which, unfortunately for the Grunts, are almost everywhere in Covenant society, since no other Covenant race breathes methane. Strangely, on the first arbiter level, the planet you go on is covered in Methane, yet the Grunts star with their gas masks on, although this could be that oxygen is inside, and the methane is only outside of the structure. The Grunts are approximately 5' tall, which does not give them any confidence when facing humans, though they lose most of their fear when using a plasma turret or a vehicle. In spite of their low rank in the caste, some Grunts have been trained with the bulky fuel rod guns and have been seen wearing black reinforced armor, implying that they are Special Ops. This does not hold with classic Covenant operation, but it seems to be the case. Because of their aforementioned tendency towards panic, disarray, and dying, the Grunts are usually herded as cannon fodder and directed by one or more of the higher caste, normally an Elite. If the higher-ranking Covenant member leading the group is killed, the Grunts will usually scatter. Grunts will usually scatter when the player wields an energy sword in the grunt's view.

Most Grunts carry single plasma pistols and sometimes grenades. They never seem to "overcharge" the pistol and take out shields, but merely shoot it in single fire mode. Some may carry plasma grenades, but are often too slow in their attempt to throw it, dying while still holding the live grenade.

Somewhere in the history of the Covenant, the Grunt Rebellion took place; possibly in the Age of Doubt. An Arbiter was created to deal with the threat.

Grunt culture has largely been erased by their incorporation into the Covenant, and they obey most of the other Covenant races out of fear because they have no political power in the Covenant. However within the Grunt community there is a strong hatred of most other species, particularly Jackals, (as evidenced at one point in Halo 2 during the Sacred Icon level) and it has been stated that the Grunts have hopes for a particularly heroic, strong, tall Grunt to one day become the savior of their kind and set them on the path to freedom by another Rebellion and the return to their homeworld. They are still used by the Covenant as cannon fodder as evidenced in the Halo 2 level, Gravemind, but they have also sided with the Elite-lead separatist faction for unknown reasons in the following level.

In Halo: The Fall of Reach it is mentioned that a reason why Grunts fight suicidally is that when they die they will go to the 'methane filled paradise', especially if they die following commands of a Covenant Elite. Some Grunts, however, are noted to not act so aggressively and suicidally; a Grunt named Yayap, for example, avoided the needless deaths of his entire squad by having them evacuate an unconscious Elite from the Pillar of Autumn.