Unggoy Heavy

Heavy is a high Covenant Unggoy rank. This rank is designated for the use of heavy weapons, turrets, and some vehicles. Even after the dissolution of the Covenant, The Covenant remnant still made use of the Heavies.

Armor
Heavy Grunts wear distinctive dark green armor, typically with a full-face methane breather and a cylindrical methane tank on their back, similar to the Unggoy Ultra. They can take much more damage than Unggoy Minors and Majors, but not as much as higher ranking Unggoy Ultras and SpecOps Unggoy. In Halo 4, the Heavies return with a visibly different, although similar, combat harness. The harness can be found in orange, red, silver, and blue colors.

Combat
Heavy Grunts are usually seen in conjunction with other Covenant infantry, operating as heavy support units and are usually operating heavy weapon systems such as Plasma Cannons, Shade Turrets and Fuel Rod Guns with deadly effect.

They will usually not flee from their position unless the player is too close or out of range of their Weapon, in which case they will pull out a Plasma Pistol and attack like a normal Grunt. They are easily dispatched using most tactics. Their armor seems to be slightly tougher than the average Grunt, most likely to protect them from explosives and the possible backfiring of their powerful weapons. Unlike most Grunts, it is strangely rare for Heavy Grunts to throw Plasma Grenades.

Note that the cannon is free for a player to use after taking out its operator. In Halo 2 a Heavy Grunt must first deploy its Plasma Cannon before it can be used. If the Grunt Heavy carrying the Plasma Cannon is killed before it can deploy it then it cannot be used. This is not the case in Halo 3, since most of the Plasma Cannons encountered are already deployed, with the exception of a few. They can still be used even if they are detached from their tripod mount.

In Halo 3, Heavy Grunts are seen utilizing many different heavy Weapons and Vehicles. They are commonly seen driving Ghosts and seem to be skillful drivers, especially on higher difficulties. Due to their low target profile, they are also much harder to kill in a Ghost from head on. Grunts will attempt to ram enemies and will keep their distance from advancing foes. Heavy Grunts may also work in teams on higher difficulties in which case one rams a foe and another shoots the foe out of what they are driving. Usually if they're not piloting a Ghost then they're manning a plasma turret or carrying a Fuel Rod Gun. Like Spec Ops and Ultra grunts, they are some of the most dangerous and tactical Unggoy. When not manning a vehicle or turret or carrying a Fuel Rod Gun, Grunt Heavies will usually use Plasma Pistols, but on higher difficulties they may use Needlers.

Trivia

 * The only time a non-Heavy Grunt is seen deploying a Plasma Cannon is in Halo 2 at the beginning of the level The Arbiter, where a SpecOps Grunt is seen carrying one. This is because the only Unggoy allies encountered in the level are Special Operations Grunts.
 * In Halo 3 Heavy Grunts are sometimes, but rarely, seen wielding Spikers. This is easier to find when the player destroys a Phantom, the Grunt will most likely (if it survived) be wielding a Spiker or a Mauler.
 * In Halo 3, if a Heavy Grunt panics while carrying an undeployed turret, it will wave the turret around in the air with only one hand. This is because Grunts usually use small single-handed weapons, and no separate animation was created for Heavy Grunts using turrets.
 * Heavy Grunts are classified as Spec-ops Grunts in Firefight, where white-armored Grunts are simply classed as regular Grunts. Spec-ops Grunts in Firefight are only seen manning the side mounted plasma turrets on the Phantoms.
 * In Halo: Reach, Heavy Unggoy have a cylindrical methane tank, same as the Ultras, and a full face mask that looks similar to a Human gas mask.
 * In Halo: Reach campaign level ONI: Sword Base, Heavy Grunts are seen with Plasma Rifles on higher difficulties.

List of appearances

 * Halo 2
 * Halo 3
 * Halo 3: ODST
 * Halo: Reach
 * Halo Legends
 * Origins
 * Halo 4