Creatures in the Half-Life series

The following is a list of creatures in the Half-Life series. Half-Life is a science fiction first-person shooter computer game series which consists of two full games, two episodic games, and three third-party made expansions, as well as a number of demos featuring exclusive content. The series has been ongoing since 1998. Most games and expansions in the series were developed by Valve Corporation and published by Sierra Studios, although some expansions were produced by Gearbox Software. Electronic Arts also took over distribution of the games in the series from Sierra from 2005 onwards. The series was initially released for the PC, but console ports of most installments have also been released. The game's setting and use of characters was influential within the gaming industry, with The New York Times writing that with the innovative storyline "Half-Life became the Citizen Kane of the genre." In Maximum PC's review of the original game the monster design was given a rating of "excellent". The complexity of the creatures progresses as the gamer advances through the game.

Creatures from Xen
Xen is where the majority of the aliens in Valve's Half-Life series originate.

Gargantua
The Gargantuan, nicknamed "Garg", is mostly blue in color, has a crocodile-like head, a thick back plating which resembles an armadillo, and has one yellow eye that glows red when it perceives a hostile unit. In place of hands, it has two claw-like appendages which can be opened to emit jets of intense heat. These claw weapons are designed to open vertically, not horizontally. Though the flamethrower weapon is short-ranged, it is still effective, known to blow up machinery, as in Half-Life: Uplink. Gargantuans can make loud roars that can damage structures. An example of the loud roars is in Uplink, near the ending sequence before the player gets trapped, the creature's loud roar made a vent collapse and the player is forced to go through and the next roar causes the vent to fall on to the platform the player gets stuck at in the start of the ending sequence. It can also send a shock wave towards its opponents by powerfully stomping the ground. This shock wave, which appears as a red dot that shoots red sparks behind it, increases in speed as it travels and can traverse vertical structures. The Gargantuan moves fast and is very strong: it can smash or toss large obstacles from its path with ease. Gargantuans are very determined pursuers, and wait patiently for their target to come out of an area they cannot reach for a considerable amount of time before moving on to do something else.

Gargantuans can be found on Xen, though their true origin is unknown. They share some physical characteristics with Vortigaunts, such as their backwards-jointed legs and hoofed feet. However, each Vortigaunt has three arms (two at the shoulders and one jutting from the chest) while the Gargantuan has four arms (two at the shoulder position and two spiked arms at the abdomen).

Gargantuans can be seen in Half-Life in the chapters "Power Up", "Surface Tension", "Interloper", and "Nihilanth". In the Opposing Force expansion, a Gargantuan can be seen in the chapter "Foxtrot Uniform" tied up on top of the hydroelectric dam, while marines and Race X Shock Troopers fight around and against it. A Gargantuan also appears during the final sequence of the Half-Life demo, Uplink, where it kills several Black Mesa personnel before slowly heading towards the cornered player, at which point the demo ends.

Half-Life 2
In Half-Life 2: Raising the Bar, an early script for the beginning of Half-Life 2 mentions that "something that resembles the old Gargantuan" was going to be seen from the train ride in the opening scene of the game. However, this introduction scene was heavily cut down throughout development, and the Gargantuan is not in the final game.

Nihilanth
The Nihilanth is the primary antagonist and the final boss in Half-Life. In the game, the Nihilanth is the controlling intelligence behind the invasion of Earth. Hovering silently in an enormous cavern, it has been commanding the forces of Xen and holding open a dimensional rift connecting Xen to Earth, enabling its creatures to attack.

Physically, the Nihilanth resembles a gigantic, oddly-proportioned fetus with its head bigger than the rest of the body, and its brain cavity forming most of the head's bulk. Its legs, minuscule in relation to its body, appear either to be vestigial or the remains of amputation. The creature sits on a large mechanical levitating contraption consisting of a large base with spikes underneath. Like the rest of the intelligent Xen races, the Nihilanth has a third appendage protruding from the middle of its chest. Its unusually long arms end in disproportionately huge hands and fingers, and it wears metallic wristbands, which look similar to bands worn by the Vortigaunts.

The Nihilanth attacks by launching energy balls, which come in two types: a swarm of purple-colored electrical orbs that causes immense damage, and a slow-moving, green-colored orb (similar in appearance to the teleportation portals constructed in the Black Mesa Research Facility) which homes in on and teleports its target to other sections of its lair populated by Xen aliens. It also uses these green orbs to teleport Vortigaunts and other Xen creatures into its main chamber to help defend it against intruders. A series of gold-colored "energy spheres" orbit around the Nihilanth's head, rendering it impervious to damage. These are consumed as the Nihilanth suffers damage from the player, but crystals resembling the one at the start of the game within the upper portion of its chamber replenish the spheres as they vanish.

Gonarch
A Gonarch is one of the creatures from Xen; only a single Gonarch is encountered by Gordon Freeman during the game. It is located within a chapter named "Gonarch's Lair" set in the border world Xen, and acts as a boss in a protracted battle that takes place in the closing stages of the game.

Description
Little is known about a Gonarch's life cycle. A Gonarch is the last stage of a female headcrab's life and, like most Earth non-human organisms with a high mortality rate, few female headcrabs reach this stage. While appearing very similar to a headcrab's anatomy, there are a few differences. Gonarchs are supported by four razor sharp limbs.

Entering a Gonarch's lair results in immediate attack. They attack by charging at their victim, then attempting to puncture them with their massive legs. They also have something of a ranged attack, by forcing yellowish balls of acidic material from the top of their shells, which they hurl through the air like mortars, raining down upon the victim. They can also launch headcrabs that will (after being launched)chase after and attack any possible threat. the smaller headcrabs are yellowish, suggesting they might be in their younger stages of life. With all their traits combined, Gonarchs prove to be skilled at defending themselves and their young, and are one of the toughest enemies Gordon faces in Xen. Upon death, a Gonarch explodes violently.

Original name
Within Valve, the creature is known as "Big Momma" (cf. its model name, ), a name given to it early on by staff developing Half-Life. The word "gonad", from the resemblance of the large sac that hangs beneath the Gonarch to a scrotum. In the book Half-Life 2: Raising the Bar, in which the following appears:

Half-Life 2
While the Gonarch is not encountered in Half-Life 2, an amputated part of it exists as an unused model file in the leak version of Half-Life 2. This amputated part, essentially nothing but the sac that hangs beneath the Gonarch's body, is covered by many metallic supports.

Bullsquid
Bullsquids are bipedal, highly aggressive creatures that appear throughout the Black Mesa Research Facility due to a dimensional rift. Bullsquids appear to be able to survive, if not thrive, in environments that are unfriendly or even toxic to humans, including sewers and pools of radioactive, chemical, or biological waste. In Xen, Bullsquids are sometimes found near pools of an unknown liquid that has healing properties to humans.

Physical description
The body of a Bullsquid is vaguely similar in appearance to that of a small theropod, with two short, muscular legs and a thick tail that tapers to a point. The thorax abruptly joins the creature's head with no neck or other visible separation. A typical specimen stands roughly one metre tall and about two metres in length. Two slit-pupiled eyes are mounted on either side of its head.

The Bullsquid's most striking feature, however, is the collection of bright red, tentacular protrusions which surround its mouth and allow it to grasp prey. Usually a Bullsquid will only attack by spitting globules of acid at enemies, but when in close range, the Bullsquid can also charge an opponent with surprising speed and force.

The Bullsquid's skin is a sandy brown covered on its upper surfaces with dark spots. The tail features a pair of prominent, outlined spots, one on either side, that are noticeably different than the dark spots on its back.

Bullsquids display a very territorial disposition, as they have often been seen attacking other creatures and even members of their own species. They viciously attacked Headcrabs in Half-Life, usually not stopping until all Headcrabs in the vicinity had been eliminated.

HD Pack/PlayStation 2 remake differences
The Half-Life High Definition Pack version and the PlayStation 2 remake version of the bullsquid features a few key physical differences from the original version.


 * The tail has a hooked claw at its tip.


 * Each tentacle surrounding the Bullsquid's mouth ends in a distinct sharp claw or perhaps more appropriately, "tooth", based on their white coloration.


 * The prominent "eyespots" on the either side of the tail are missing.


 * The eyes are black and glossy as opposed to white and relatively dull on the original version.

Offensive abilities
The bullsquid has an array of offensive capabilities: At close range, a hostile bullsquid will either maul its victim with its teeth, or suddenly spin around, delivering a powerful strike with its tail, often causing a gibbing. Additionally, the bullsquid is able to "spit" a toxic, bile-colored substance from its mouth. While not overly accurate or fast, it causes moderate damage, even at long range.

Half-Life 2
While not in Half-Life 2 itself, the book Raising the Bar explains the creatures were, at least, going to be visible or mentioned during it. Dr. Eli Vance's lost leg was to be explained as a result of a bullsquid attack, and one of the scenes during a plot-reveal scene would have shown bullsquids frolicking outside a supermarket.

Grunt
The Grunt is of Xenian origin and is one of the more intelligent species of Xen. It shows considerable sentience making it a formidible opponent. It sports the deadly HiveHand weapon, which fires vicious, small homing insects, and also has purple, organic shoulderpads and helmet. It is also roughly 7 to 8 feet tall, making it rather intimidating, unlike other species. They can work in squads or pairs as well making them one of the more dangerous enemies around.

Houndeye
The Houndeye, or Sound Dog, is one of the alien species which appears in Black Mesa following the opening of a portal to Xen, and has an appropriately alien appearance. Possessing three legs and only a thorax, the Houndeye is a faint yellow-green in color, with electric blue tiger-like stripes adorning the spine of the animal. In place of a head there is a large, black, compound eye that is protected by sideways-blinking eyelids. They apparently communicate through a series of high-pitched sounds somewhat similar to the barking of dogs.

The Houndeye is an example of a social animal in terms of pack hunting. While a shy and timid creature by itself, groups of three or more creatures display resonant behavior, emitting destructive harmonics capable of injuring those they attack. This behavior came about through Valve's original plan of Houndeyes being neutral or even friendly towards the player, until they realized playtesters shot them down regardless and dropped the idea.

Although they are not seen displaying this trait often, Houndeyes appear to be carnivorous creatures, as one is seen eating a dead security guard in Half-Life: Blue Shift. A Houndeye's mouth is located on the underside of its belly, close to the eye, filled with what appears to be fang-like incisors.

The Houndeye is the only remnant of a type of creature that was to be more common in Half-Life. Originally there was to be a "Panthereye" creature, similar to but stronger than the Houndeye.

According to the book Half-Life 2: Raising the Bar, Houndeyes were one of the enemy types in the early Half-Life 2, first seen by the player on an old projector slide in which they and Bullsquids terrorized an American suburb. The texture for the Houndeye's compound eye was to shine and could reflect its surroundings. Houndeyes could also work in herds, led by a dominant Houndeye, and had faster movement speeds.

Chumtoad
A Chumtoad is a toad-like Xen creature; it was originally designed for the first game of the series, Half-Life, but not included in any official game until one cameo appearance in Half-Life: Opposing Force and two in Half-Life: Blue Shift. It has not appeared in any official game since.

Description
Chumtoads are small, amphibious creatures found on Xen. Similar in morphology to Earth's toads, they are very low on the Xen food chain – serving as the favorite prey of many Xen creatures. Chumtoads have a bright purple coloration, and a single red, catlike eye, spiked backs, and long, blue tongues.

Unlike most Xen creatures, Chumtoads are not inherently dangerous to humans. They tend to lounge on rocks until threatened, at which point they can teleport, vanishing in a puff of purple energy.

Chumtoads maneuver with short, quick hops, and can swim and leap to great heights if startled.

Habitat/"Chumtoad's Lair"
To date, only one environment containing Chumtoads has been discovered in a Half-Life game. Its location is in the chapter "Focal Point" of Half-Life: Blue Shift. After arriving on Xen, Barney Calhoun enters a series of cramped, narrow tunnels full of headcrabs. Nearing the exit of this maze, he passes through a large cavern with a deep pool at its centre.

At the bottom of this pool, between a boulder and three Xen plants, a small crack in the wall of the cave can be seen emitting bubbles of air. After widening this hole, the player can enter a small air pocket in a cave where the title "Chumtoad's Lair" appears on the screen. In the lair, three Chumtoads sit among Xen plants and snark nests, illuminated by Xen crystals. The creatures later vanish when approached.

Development
The original role of the Chumtoad in Half-Life was as bait that a player could use to lure or distract enemy aliens. The bait idea was never developed, and the Chumtoad was eventually cut from the game.

The unused model, however, was included in the game's files and fully coded as an item. Instead of bait, this version served as a weapon. Normally docile until picked up, the Chumtoad would begin attacking anything that strayed too close – including the player or allied NPCs if no other targets were available. This AI was implemented in the final game as the behavior of Snarks.

The source files for the Chumtoad are included in the Half-Life SDK, where it is referred to as a "Chubtoad". According to the textures provided, the Chumtoad was once planned to have six eyes instead of one, and would have had green, orange, and blue-colored variations.

Barnacle
Barnacles are scavengers that hang on the ceiling and drop down a very long, highly adhesive tongue. When something gets caught on their tongue, they retract it, in an attempt to eat it. If the object is edible, they consume it. If not, they drop it and await new prey. Barnacles appear in Half-Life and Half-Life 2. Barnacles are usable as a cross between a weapon and a biological grappling hook in Opposing Force.

Snark
Snarks are small, insectile beings of a deep red hue, approximately the size of a human hand. They have a single, green eye on the front of their body. Snarks have four legs, and a pair of pale blue-green pincers on the front of their bodies that they use to attack. In the game, the player is able to use snarks as weapons, by hurling them at enemies, and in the multiplayer version of the game, players can hurl snarks at each other, as in the single-player game. The creatures soon tear through seemingly most organic materials, and so they kill their human victims within a matter of seconds. They are fast and can leap very high, so as to bring down larger opponents.

Snarks seem to be physically and chemically unstable, as they explode into a green goo after a set amount of time after being launched. Shooting or hitting them will also make them "pop".

On the multiplayer game map named Snark Pit (snark_pit), the eponymous snarks are contained within a metal pipe at the top of the area, which is made up of four levels, each of which can be accessed by stairs or ladders, as in other maps on Half-Life. The pipe overhangs successive holes which are in line with each other, and therefore anything dropped or thrown down will fall through the holes consecutively and reach the bottom area within a short amount of time (however, this is not recommended for players, since the impact of the fall will kill a player) The player can activate a button near to the pipe to open it and thus release snarks into the lower areas of the map, meaning that on multiplayer, anyone spawning or respawning at the bottom will almost certainly be chased by snarks. After a set amount of time, the snarks will explode and the pipe will close. For some unknown reason, the player only seems to be able to release the snarks once in a game.

Race X
Race X is a hostile, non-Xen alien race. They appear only in the Opposing Force expansion pack, and very little is revealed about them. Race X aliens appear late in the timeline of Half-Life, a few hours before Gordon Freeman teleports to Xen.

Pit Drone
Pit Drones are the second type of Race X aliens encountered in the game. They are short bipedal creatures with yellowish-tan skin and a small head with rows of sharp spines.

A Pit Drone's arms end in long, scythe-like claws, which it can use to make vicious attacks. Fast and fairly intelligent, they tend to appear in groups of five or six, and are capable of making flanking movements and quickly surrounding their prey. They have two forms of attack: firing their head-spines like darts through acid jets when at long range, or charging towards the target to deliver a deadly slash with their claws. Some Pit Drones appear not to be capable of the head spine attack and, on closer inspection, have no spines in their head. It is notable that when Pit Drones are first encountered, they create light thumping footsteps while dashing through a long vent grate above a garage area.

Shock Trooper
Shock Troopers are the first encountered and most intelligent of the Race X aliens. Physically, they are humanoid with four arms and have a posture that makes them vaguely resemble Vortigaunts. Their bodies are covered in plate-like sections, similar in appearance to insect exoskeletons. Their skin is pale blue, and is not mottled or patchy like the skin of Xen creatures. They have a single large eye, Vortigaunts also have one eye. This eye is apparently part of a common morphology between Race X creatures - every Race X alien with a large eye (including the Pit Worm) has two eyelids which regularly blink horizontally across the eyeball and what appears to be "tentacles" surrounding their mouth (which is under the head).

Their primary weapon is the Shock Roach; a living creature, similar to the Alien Grunts' hive-hand. The Shock Roach fires bolts of electricity, which it constantly recharges on its own. The Shock Roach cannot survive without a living host for very long; if its Shock Trooper dies, it will detach itself and pursue a new host. If it nears a player that already has a Shock Roach, it will attack before dying.

Shock Troopers also have the ability to regurgitate and throw spore grenades, which they tend to use against distant or concealed enemies; they also have a very lethal melee attack that is capable of tearing Shephard to pieces by scratching him with their arms. This 3rd attack is only used when approached toe to toe. Infant Shock Troopers will forcibly launch the same type of spore grenade when squeezed, and can thus be used as a Spore Launcher weapon. In one of the Spore Launcher's idle animations in Opposing Force, it emits an amphibious purr, at which point Adrian Shephard strokes the top of it back and forth as if it was his "pet".

Baby Shock Troopers are effectively tadpoles, an earlier stage that is only a head and torso, with tentacles trailing behind. Beyond the small size and lack of limbs, Baby Shock Troopers also have gills and two small eyes instead of the adults' single large one. They are amphibious, although immobile outside water. Baby Shock Troopers are first found in a tank in the Sector E Biodome Complex of Black Mesa.

Shock Troopers are usually encountered in small groups, and fight together with other Race X aliens. Shock Troopers have a verbal form of communication.

Shock Troopers use teleportation technology to travel in and out of combat. They also control the teleportation of Pit Drones and Voltigores.

Voltigore
Voltigores are gigantic, lumbering creatures serving as the race's heavy support infantry. Voltigores have four legs and two arms that end in scythe-like claws, and are distinguished by purple stripes on their bloated carapace similar to those on a houndeye, though in a different color. These aggressive creatures use their innate ability to harness electrical charges to create a devastating ranged energy ball attack, bearing vague similarity to the Vortigaunt's green energy stream, although the Voltigore's energy attack is purple, an avoidable projectile and is more powerful. At close range, they attack viciously with their claws. A player can recognize a Voltigore from afar by the unusual, electric-sounding bellows of the creature. When a Voltigore dies, its carapace explodes, causing massive damage to nearby creatures.

Baby Voltigores appear later in the game. They are smaller, weaker, lighter in color, and use the energy attack in a lighter way.

Pit Worm
Encountered in a sewage processing area in the lower levels of Black Mesa, the Pit Worm is composed of a segmented body which supports a head dominated by a single large eye. This eye is the pit worm's primary weapon, capable of firing a searing energy beam at nearby enemies. If enemies get too close, the worm also has large claws to strike with. If the worm is shot in the eye, it recoils, shielding it with its claws for a few seconds before striking aggressively at the player.

Gene Worm
The Gene Worm is the final boss of Half-Life: Opposing Force. This life form is the equivalent of a "biological resource management factory." It is capable of taking any of Earth's natural resources and assimilating them to make them useful to the aliens' needs. If one fully entered Earth and became productive, it would effectively alter the planet enough to become useful as a new homeworld for Race X.

Physically, the creature resembles a green, worm-like creature with many tentacles, with a beak-like protrusion similar in both shape and position to that of the Xen tentacle. The Gene Worm attacks with its tentacles and also ejects a deadly chemical stream from its mouth. Its outer hide is impervious to damage; in order to kill it, the player must blind the creature by shooting both its eyes with the mounted laser guns on either side of the worm. This causes it to summon reinforcements by opening its abdominal cavity, revealing a portal orb that a Shock Trooper will teleport through.

The Gene Worm is found deep underground in a seemingly abandoned industrial area of Black Mesa, and appears through a portal opening in a room there. The room itself has been fitted with mounted weapons which are powered by Xen energy crystals. The player character, Adrian Shephard, is sent down to the portal by a Black Mesa security guard, who remarks "Some of your buddies went down earlier, and I haven't seen 'em since."

Ten years later Gearbox would re-visit the Gene Worm encounter as another final boss in their 2009 video game Borderlands.

Sprite
Taking on the appearance of what looks like a flying ball of light, Sprites are creatures that can be seen floating through the facility several times during the game, becoming more frequent in later stages of the incident. However, they cannot be harmed and do not hurt the player in any way. On occasions they even seem to be guiding Adrian. In the scenario where the Gargantua is trapped on the Sector G hydroelectric dam, sprites fly into a portal nearby which the G-Man then steps through. They eventually all lead to a massive violet portal that brings the Gene Worm in. At the time Gordon Freeman pushes the Xen crystal into the Anti-Mass Spectrometer, many Sprites fly towards and away from the resonance cascade, the former of which also happens when the portal to Xen in the Lambda reactor core is fully opened.

Antlion
Antlions are bugs from Xen, and first appear in Half-Life 2. Antlions are similar to ants in their "hive" behavior. All types of Antlions are found in the Nest in Half-Life 2: Episode Two. Here are the types of Antlions that appear in the games:

Antlion
Antlions are green striped creatures that were discovered in beaches along the coast near City 17. Regular Antlions are not much of a threat alone, but endanger the player when in groups. Antlions appear to possess some intelligence in that they are the only non-human enemy that will actively try to flank or surround the player. In the chapter "Sandtraps", it is discovered that, if the player steps on the sand, it "drives the Antlions crazy" and makes them surface and attack. After the player kills the first Antlion Guard he or she fights, a Vortigaunt comes and removes the Antlion's pheropod, informally known as bugbait. The player can use the bugbait to call on the Antlions as allies, as they are attracted to the pheromones, and no longer see the player as a threat. In Half-Life 2: Episode One, Antlions come into City 17 because the Combine Defense field was destroyed. Antlions come through burrows like in the level Nova Prospekt.

Antlion Guard (Myrmidont)
Antlion guards, also known as Myrmidonts, are among one of the most feared creatures and the most powerful in the Half-Life universe. Their aggression surpasses that of the regular Antlion. They are larger and more armored, and faster than the regular Antlion itself. Antlion Guards prefer to charge at the player, and will attempt to headbutt the player. They are also able to throw physics objects like zombies can, and are the only organic NPC in the game that can't be destroyed with a single hit from the AR2's alt fire.

A large part of Episode Two is spent running from a version of the Guard. See "Antlion Guardian" for details.

Antlion Grub
Antlion Grubs are small, worm-like creatures that usually reside in Antlion nests in Half-Life 2: Episode Two. They affix themselves to walls, ceilings or floors and do not move. Grubs are very weak, and they cannot attack. They are easily killed with one bullet, or even by being stepped on. When killed, they drop small yellow "grub nuggets" that restore one to six points of health to the player, depending on the size.

It is an achievement in Half Life 2: Episode Two to kill every Antlion grub in the game.

Antlion Worker
Antlion Workers or Acidlions are luminescent types of Antlions, though they are stronger, spit acid, and resemble termites. They also are somewhat more defensive in their attack strategy: they will stay at range and retreat when advanced upon, and are capable of flanking the player or leading the player into traps. Antlion Workers are usually found in the Antlion Nest in Half-Life 2: Episode Two. Like all Antlions, Workers also hate thumpers. Usually the Antlion Workers are the ones guarding the Grubs.

Antlion Guardian
Antlion Guardians are similar to the Antlion Guard, but are green and have a neural-poison attack when underground. The Guardian guards the path to the Extract, which is used by the Vortigaunts to heal Alyx Vance after she is wounded by a Hunter.

Hazardous Environment Combat Unit
The Hazardous Environment Combat Unit (HECU) is a US Marine Special Forces detachment in Half-Life created to deal with dangerous environments not suitable for ordinary forces. During the Resonance Cascade, they are deployed in massive force to the Black Mesa Research Facility to eliminate the alien threat, and cover up the incident by eliminating the Black Mesa staff. However, the job is too big for them. Running low on supplies and taking constant casualties from the never ending waves of Xenian Aliens, they begin an immediate retreat. All military personnel are ordered to evacuate the base. Unfortunately many don't make it to the rally point in time and are left to die. Of those left behind during the evacuation, Corporal Adrian Shephard is the only known survivor.

Equipment
The HECU use a variety of weapons and equipment to get the job done. They use M35 2-1/2 ton cargo trucks, M3 Bradley IFVs, and V-22 Osprey Helicopters to deploy troops. M1A1 Abrams MBTs, M6 Linebackers, and AH-64 Apache Helicopters are used as heavy support units. The Infantry primarily use MP5 SMGs (or M4 Carbine Rifles in the HD pack) with an M203 Grenade Launcher attached, SPAS-12 Shotguns, and in Half-Life: Opposing Force, M249 SAW LMGs. Infantry units are issued high tech Powered Combat Vests to protect them from a variety of hazards including gunfire, explosions, electrocution, and toxic chemicals.

Combine
The Combine, also referred to as the Universal Union, is a fictional multidimensional empire, which serves as the primary antagonistic force in the Half-Life video game series, developed by Valve Corporation. The Combine consist of alien, synthetic and human elements, and dominate Earth. They are regularly encountered throughout Half-Life 2 and its episodic expansions as hostile non-player characters as the player progresses through the games in an effort to overthrow the Combine occupation of Earth.

The Combine are frequently shown as harsh rulers over the citizens of Earth, suppressing dissent with brutality, policing using violence and using invasive surgery to transform humans into either soldiers or slaves. Throughout the games, the player primarily battles with transformed humans as well as synthetic and mechanical enemies that are the product of Combine technology. The atmosphere generated by the dystopian Combine state has been praised by reviewers, although the artificial intelligence of the transhuman Combine characters was thought to be inferior to that of other characters in Half-Life 2. In addition to their role within the Half-Life series, the Combine have been adapted for machinima productions and one synthetic enemy character of the Combine has been made into a plush toy by Valve.