Unggoy Ultra

Ultra is the the highest known Unggoy (Grunt) Covenant rank.

Rank
The Ultra Grunt is the highest Unggoy rank seen so far in the Covenant military so they must be the Grunt equivalent to a UNSC Sergeant. Like Ultra Elites, Ultra Grunts wear distinct white/pearlescent armor.

Ultra Grunts can sometimes be seen commanding lower classes of Grunts in battle, even leading black-armored Special Operations Grunts into combat, and is rare for the player to find them when playing Halo on lower difficulties, such as easy or normal.

Unlike Ultra Elites, Ultra Grunts do not appear to have any immunity with their command. It is just as likely that two or three will be encountered leading a small group of Grunts, yet the Elites, or Brutes in the Loyalists, are ultimately in complete command. These Grunts, like their lower-ranking cousins, appear in groups. They are very intelligent, making as few tactical errors as Major Domo Elites.

These Grunts usually display more bravery in combat than a Spec Ops unit and are more often used for general missions, rather than specialized attacks.

Combat
Ultra Grunts usually throw more grenades and are far more accurate and deadly at a greater distance than the lower ranked Major and Minor Grunts. They are usually seen with Needlers or Plasma Pistols. They can also take the same amount of damage Spec Ops Grunts do, but they are still vulnerable to head shots (even though it may take more than one). Like SpecOps Grunts, they are rarely caught sleeping on duty. They still panic if they know that they are being overwhelmed, but are more likely to go berserk than panic-especially if one of their comrades was killed by a grenade. An Ultra Grunt compared to an average Minor Grunt can take much more damage and usually takes two to three melees instead of one to be killed, even on lower difficulties like Normal. In Halo 3, even if you have the Thunderstorm Skull on, Ultra Grunts will still run away if you kill their leader. If Ultra Grunts run away and you follow one it will turn around and start firing at you. They are the ones that command small squads of Grunts when a Elite or Brute is not present or have been killed and are very good and effective leaders.

Background
The purpose of this rank designation has been generally unclear. They were first mentioned in Halo: First Strike, pushing carts of cleaning fluid, implying that they were even lower than Grunt Minors. However, they were also seen inside the Scarab walker in New Mombasa along with high-ranking Elites (Minor, Major, and Ultra). They were also seen throughout New Mombasa, Delta Halo and Cairo Station. This led some to believe that they were "technicians" or engineers (Not to be confused with the Engineer species) of some sort, but the production book, The Art of Halo, confirms that they outrank Major Grunts. It has, however, been suggested that white armor actually signifies manual labor, while the more silver armor signifies Ultra. Still, there is not a sufficient color difference to make this a significant case. It may simply be that when author Eric Nylund wrote the book, he chose the color white because it was a color not previously seen in Halo: Combat Evolved, and did not know that Bungie would choose a similar color for the new Grunt rank or possibly that even though they are high ranking Grunts, they are not free from manual tasks. The rank is a rare achievement for an Unggoy, due to the fact that this species has a high death rate. Ultra Grunts most likely delegate a great degree of respect from the Grunts under their command, as their combat prowess must be exemplary, or they are just very lucky.

Appearances
These Grunts are seen in both Halo: First Strike and Halo 2. They are seen throughout Halo 2, but are far more frequent in the Heroic or Legendary difficulty levels than the Easy or Normal ones.

Halo: First Strike

 * Unyielding Hierophant- Two Ultra Grunts were seen pushing carts of cleaning fluid.

Halo 2

 * Cairo Station (Easy and Normal less common, Heroic and Legendary more commonly)- Seen throughout the level, most noticeable are in the hangars, but also in the Commons areas.
 * Outskirts - Ultra Grunts attacked SPARTAN-117's position in the building near the Pelican crash site.
 * Metropolis - A few Ultra Grunts were present on the Scarab command deck.
 * The Oracle - An Ultra Grunt is dropped to help the Arbiter with some other Spec Ops forces at the exit of the Flood labs.
 * Gravemind (Legendary only) - Ultra Grunts aid the Brutes at the beginning of the level.
 * Uprising - If you are lucky, the Grunt assisting you in the turret will be an Ultra. This is very rare, though. On Heroic and Legendary, two Ultra Grunts are present near this turret.
 * High Charity - At the beginning of the level and a few more times throughout the whole level, they are seen fighting the Flood.

Halo 3
It is in dispute as to whether the silver colored armour Grunts wear in Halo 3 are Grunt Ultras. Those for the existence of Grunt Ultras in Halo 3 point to page 131 in the Official Guide, which discusses Ultras and has a clear picture of a silver colored Grunt and a black (presumably Special Operations Grunt) Grunt, while skeptics maintain that the lack of pictures of such black colored Spec Ops Grunts, and the Bungie scoring system refute the existence of Ultras in Halo 3. However, the Ultras are probably the highest ranking Grunt still on the side of the Covenant. Also, the presence of so many Ultras in Halo 3 is strange, without any Spec Ops Grunts to command. Also, when the Thunderstorm Skull is activated, all Grunts get this silver armor, except for the Gunner Grunts.

Trivia

 * In Halo 3, the Grunt Ultras' armor is more of a pearly white color rather then plain white or silver.
 * In Halo 3, if you knock off the methane tank of a Ultra Grunt, the tank's color will turn orange like the Grunt Minor's tank. This also happens to all Grunts.
 * In the Halo 3 instruction manual that comes with the game, for the description of Grunts, there is a picture of an Ultra Grunt.
 * In Halo 3, if you put the Thunderstorm Skull on and play on a lower difficulty, when you kill a Brute, then the Ultra Grunts might run away.
 * Sometimes, an Ultra Grunt's armor appears slightly darker, possibly meaning that they are more experienced Ultra Grunts.