Jiralhanae Stalker

The Stalker is a Brute (Jiralhanae) rank.

Stalkers are covered in gray armor and possess integrated circuitry for Active Camouflage in their Power Armour. They often use Radar Jammers to confuse their prey and are the main users of Incendiary Grenades. It is unknown how Brutes are promoted to this rank (possibly the number of casualties they inflict), but they are commonly seen acting as spies and bodyguards for Brute Chieftains. The Stalkers replaced the Special Operations Elites of Halo 2 after the Elites became Separatists from the Covenant. McFarlane is also going to release an action figure of a Brute Stalker for its second series of action figures.

Appearance
The Brute Stalker does not appear in Halo 2 and is featured in the Halo 3 levels: The Ark, and The Covenant. They use their active camouflage to protect their Chieftains. The armor is a misty blue and covers the legs. A large helmet hides their eyes and a red/orange light, possibly a laser sight, sits on the helmet front.

Combat
Stalkers often employ Plasma Rifles and Incendiary Grenades in battle. Once you spot the distinctive visual disruption caused by their active camouflage, use your weapon and melee them. They will be stunned and temporarily visible. Follow up with more melees until they're dead. Charge a Plasma Pistol and fire at the movement shimmers and it will usually strip their power armor. While the Brute may go berserk, dodge the physical attacks and finish off with a melee. On higher difficulties, it is advised to use grenades, as they will blow their cover, and they can be quickly finished off by an automatic weapon. Watch for enemy fire and destroy any Radar Jammers you see deployed on the ground. Using the Power Drain will also strip their armor off, resulting in them being visible. Another way to spot a Stalker is, if the Stalker is standing on a glass floor, look at the glass, and their feet will be visible. Defeating them is the easiest way to get incendiary grenades.

In the official Halo 3 guide it states that there is a 'Brute Tracker' No such Brute has been found though it may be that they were cut from the game or are higher ranking Stalkers.