Tough, strong, and extremely hostile, Alien Grunts stand about seven feet tall and are armed with a biological weapon called the Hivehand which launches living projectiles: autonomous, insect-like creatures known as hornets which home in on their targets. At close range, they will also use hand-to-hand combat. Alien Grunts share many physical characteristics with their Vortigaunt counterparts: multiple red eyes, backwards-jointed legs, hoofed feet, and a short arm extending from their mid-torso which is used for feeding.
They are equipped with metallic-like armor around the groin and shoulders, as well as helmets and shoes. However, several areas of their body are still left exposed. Alien Grunts take significantly reduced damage if shot in the armor rather than their exposed flesh with a .357 Magnum or Crossbow; lower impact rounds, such as pistol or Submachine Gun bullets, buckshot, and even the primary fire of the Tau Cannon, will outright ricochet off the armor without doing any damage at all since the protection negates 20 points of damage from many sources.
Alien Grunts use intelligent soldier-based combat tactics, for instance running between cover and firing at unseen enemies so that the hornets will track foes around corners. They have almost twice as much health compared to HECU Marines. Combined with their bullet-deflecting partial body armor, this gives them high durability in battle. They also demonstrate superhuman strength in various scripted sequences seen throughout the game, such as punching a soldier through a concrete wall, quickly prying open a large set of heavy blast doors, and thriving in harsh conditions and high radiation areas.
Alien Grunts can be found being transported through the mines on Xen stored in pod-shaped containers. They are also often transported by Alien Crafts. At one point in the game, a group of Alien Grunts appear to have set up an Energy Cannon, implying the necessity for external weaponry.
 Behind the scenes
The Alien Grunt was initially known as the Alien Warrior Vortigaunt. Before the Hivehand, the Alien Grunt was planned to use different type of weapons. An early version of the Alien Grunt model had blue armor (initial concept art featured green armor while early model renders depicted a bright silver armor) and lacked the Hivehand, instead firing hornets directly from its right hand. This model was kept in the retail Half-Life as a sprite for the Alien Grunts forming the distant back rows in the "bad" ending. The final Alien Grunt model also features an unused variation in which it lacks a Hivehand akin to its early model.
In Online Gaming Review's early Half-Life Monster of the Week Feature preview, Alien Grunts were given the taxonomic designation "Xenotherium myrmex." The creatures discharged from their Hivehands are referred to as "thornets," and their regeneration is explained as being as a result of continued breeding in their host's para-coelomic cavity. The Alien Grunts' armor is described as not being a product of alien technology but rather a biologically extruded exoskeleton synthesized from a diet rich in certain xenotic minerals. Their preferred ration is said to come in the mobile form of Chumtoads, an alien type which ended up being cut and not appearing in the original Half-Life.
 Half-Life Alpha
Ditto, facing off against Gordon Freeman.
Human Sergeant, Alien Grunt, HECU grunt, and dead scientist in a tunnel.
Alien Grunt and two dead scientists in an early Datacore map which originally was to appear in singleplayer.
Alien Grunt firing an early Hivehand which resembles the Alien Organic Assault Rifle.
High Definition version.
Ditto, Source version.
Alien Grunts being unloaded by an Alien Craft.
A Grunt standing near a Snark Egg.
An Energy Cannon.
 List of appearances
- Half-Life (First appearance)
- Half-Life: Opposing Force
- Half-Life: Blue Shift
- Half-Life: Decay
- Half-Life 2: Raising the Bar