Special Operations Unggoy
From Halopedia, the Halo wiki
Summary
Special forces unit of the Covenant. Special Ops Grunts are skilled fighters, they are much more intelligent than their "regular" counterparts. They are not to be taken lightly. They are only called in during special combat situations, and hold a unique amount of respect for a member of their race. They are highly trained and only commanded by the skilled Special Ops Elites Sometimes they are even equipped with Active Camouflage.
Combat
SpecOps Grunts almost never panic during combat, as Minor and Major Grunts do. They often wield Needlers, Fuel Rod Guns, and Plasma Grenades. The biggest concern of facing a SpecOps Grunt, however, is that a SpecOps Elite is more than likely nearby. SpecOps Grunts are not to be underestimated, though.
They usually move in teams of two or three, in which case it is best to target one holding a Fuel Rod Gun as his teammates may be killed when it explodes. These grunts are faster and sometimes it takes multiple headshots or melee attacks to kill them.