The Theron Guard represents the elite of the Locust, head-and-shoulders above the lowly Drones in terms of equipment, intelligence, and training. They are elite Locust, assigned to commando-style raids against high-profile targets and high-level defensive missions that require the sort of precision the Therons possess. If the Drones and Boomers represent the Locust military's hammer and anvil, then the Theron Guard is most decidedly its scalpel.
Therons are easily recognized from other Locust - they wear heavy body armor that covers more of the upper body than drone armor and a long, leather-like strip of material hanging from the back of the waist that trails behind them as they move and gives the impression of a trench coat combined with armor. Many wear distinctive-looking helmets as well, often heavily embellished. Theron Armor is chased with bright red flecks, presumably to give them a more-imposing appearance. Their voices are sibilant and with a definitive, whispering hiss, giving them a distinctly menacing presence. Though it is more intimidating, the hissing and whispering can be a big give away to the opponent of your position. Higher-ranked Therons are called Theron Sentinels and serve as sergeants in Theron Guard force groups. Theron sentinels are slightly taller, wear a slightly deeper shade of red armor, and have a round helmet with no visible eye slits. The differences in visible appearances are minimal and easily overlooked in the heat of combat, but so are their stat upgrades so don't fret about it.
Therons usually operate in small squads, led by a Theron Sentinel that serves as a Sergeant, though this is not always the case. They clearly out-rank both Drones and Boomers, and can be seen ordering both Locust subspecies around - in several scenarios you can encounter a single standard Theron leading a squad of Drones. They can also be found making use of Bloodmounts and Reavers. As elites, Therons are more powerful, accurate, and better-armored than their contemporaries, and they are invariably better armed as well, making them a significantly greater threat than the rank-and-file Locust.
Most Therons use the Torque Bow as their weapon of choice. Because of this, they are a deadly threat capable of instantly killing an unprepared Gear from a considerable distance. They also make use of the Lancer Assault Rifle, Hammerburst Assault Rifle, and Gnasher Shotgun, as well as the Boltok Pistol. Unlike Drones, Therons are smart enough to make use of dropped weapons, so if an allied Locust dies in their presence, they may raid their corpses for weapons or ammo. So a Theron may utilize a fallen Grenadier's Bolo Grenades or Gnasher Shotgun.
As elites, Therons make extensive use of cover and ambushes, and are smart enough to know when a battle is turning against them. Expect them to flee rather than die if they take too much damage, and for other Locust to aid the Theron if they become injured. They frequently send Drones and Grenadiers forward as cannon fodder and to force Gears out into the open, so they can cut them down piecemeal. They also often feign retreat, in order to lure enemies closer and into pre-set firing lines, so be aware of their tricks and don't be fooled.