The Unggoy, also referred to as Grunts, are an alien race and one of the many species that make up the Covenant Empire. They are antagonists in the Halo franchise.
The Unggoy were the fourth alien race to join the Covenant alliance and are the lowest-ranked race in the Covenant hierarchy, typically being used as laborers or cannon fodder in combat situations.
The highest ranked Grunts within they Covenant Military, clad in white/pearl colored armor. They can be seen commanding lower-class Grunts and even Special Operations Grunts. Unlike Elite Ultras, Ultra Grunts do not appear to have any immunity with their command yet the Elites or Brutes have complete command. Similar to Prophet Minors outranking Elite Shipmasters, Ultra Grunts are inferior in rank to even Elite Minors. These Grunts, like other Grunts, appear in groups and are very intelligent, making as few tactical errors as an Elite Major. They usually display even more bravery than SpecOps Grunt units, showing more often specialized attacks rather then generic military operations.
Special Operations Grunts
Unggoy who have been given proper training, allowing them to acquire specialized roles and give excellent support to Special Operations teams. Generally tougher, smarter and certainly more aggressive than their lesser brethen, SpecOps Grunts are always deployed with SpecOps Elite team leaders and specialized equipment and sometimes are led by Ultra Grunts. If a SpecOps Grunt's leading Elite is killed, instead of panicking and fleeing away from the enemy, they will often seek revenge, finding cover and sending Plasma Grenades and plasma shots accurately at the person who killed the Elite. A number of SpecOps Grunts assisted SpecOps Elites led by Rtas Vadum and Thel 'Vadam in assaulting the a Heretics Gas Mine and successfully assassinated the Heretic leader, Sesa Refumee.
Grunts specialized in use of heavy weaponry, turrets and small vehicles. They are often found operating as heavy support units and usually operate heavy weapon systems such as Plasma Cannons, Shade Turrets and Fuel Rod Guns with deadly effect. During the Fall of Reach, Heavies are usually seen operating plasma turrets on Wraiths. They will not usually retreat from their position unless if their out of range or too close to use it, then they will pull out Plasma Pistols to act as a standard Grunt and fire at the player. Unlike most Grunts, Heavies rarely throw Plasma Grenades nor suicidal attack. In Halo 2, Heavies usually carry and man Plasma Cannons. On Halo 3, Heavies are usually deployed in Covenant Watch Towers to fire with Fuel Rod Guns or with a Plasma Turret.
Higher in rank than Minors and decorated in lucid red-colored armor. They are better in terms of strength and intelligence, than Minor Grunts and often more courageous as well, often staying to fight under conditions that would make their lesser brethren flee. They lead small squads of Grunt Minors into battle and usually fight alongside a combined team of other Unggoy and Kig-Yar. They are seen in combat as (similar to their Elite counterparts), contrary to the orange armor of Minor Grunts. If their superior officers are killed, Majors will typically flee alongside the rest of their troops, though they will sometimes continue to fight.
The lowest rank in the Unggoy system of hierarchy, they fill the role of expendable cannon fodder. Though not much of a threat individually, they provide much more of a threat in large numbers. They are among the most common in the Covenant Infantry. If their squad leader is killed, most Minors will flee or attempt to take cover, but some will charge plasma grenades and attempt a suicide bomb.