The main hero of the Half-Life series, Gordon Freeman is, at the point where Half-Life begins, a recently graduated scientist who is about half a hour late for an experiment, taking place deep within the Black Mesa Research Facility. If only he had known that it would soon become the least of his worries that day...Finding himself at the ground zero of a disaster, trapped between an invasion of aggressive creatures from the dimension Xen and a shadowy military force that wants him and his colleagues dead, Freeman manages to battle his way across the facility in the span of two days, staying alive against all odds, aided by his HEV suit and staunch determination. He is eventually teleported to Xen, where he takes on the leader of the aliens, after which he finds himself face to face with the mysterious G-Man, who offers him a job.Displaced by G-Man in time and space, Gordon suddenly finds himself in the so-called "City 17", in some undisclosed part of Eastern-Europe two decades after the events at Black Mesa. He discovers that Earth has been conquered by an alien empire called "The Combine", who rules their new colony with an iron fist, and he quickly manages to run afoul of them and is soon hunted by their military. But he also finds out that some of his old friends from Black Mesa has organized a resistance group that fights against the regime, and that he himself has become a revered and famous figure for the rebels due to his actions at Black Mesa. Together with the resistance fighter Alyx Vance, he ignites a full-scale rebellion against the Combine, and manages to bring down their central control-center on Earth.In the wake of the overthrow of the Combine control, however, Gordon and Alyx, along with the rest of the rebels, soon finds themselves engaged in a even more bloody and desperate struggle to defeat the remaining Combine forces on Earth, and, even more importantly, preventing them from contacting the empire proper for reenforcements...
Asskicking Equals Authority: By the time of Half-Life 2, he doesn't have any definitive rank in the rebellion, but he pretty much commands any rebel squads he comes across, who are all too willing to Zerg Rush a position if he so much as looks at it, all because he's good at killing things.
The Dreaded: He steadily builds up a reputation throughout his adventures in Half-Life; by the midpoint of the game, the marines know exactly who he is and are actively hunting for him specifically. By the end, the Nihilanth is able to directly address him by name.
Dude, Where's My Respect?: Averted. His reputation actually seems to do more work than him. He's pretty badass, but it was his reputation, not his actions, that caused most of the rebellion on Earth against the Combine.
One-Man Army: While his suit is a big part of it (it gives him about 4 times as much health as a regular soldier when fully charged, can automatically reload his holstered weapons, and applies morphine and other assistance to keep him going at full strength even when badly wounded), it is still pretty amazing considering he is just a scientist.
The best example is probably at the end of Episode 2. The rebel's main headquarters comes under attack from multiple directions. Dozens of combine Elite Mooks storm through the roof on dropships and set up numerous defensive positions, a bunch of Hunters break in to support them, and a dozen striders, each supported by 2-3 Hunters, start attacking the base. After the rebel personnel get completely slaughtered, they just send Freeman, thinking that he's all they'll need to repel hundreds of heavily armed and armored dark energy rifle wielding super soldiers, and a bunch of giant tripod death machines supported by dozens of other, smaller tripod death machines. They're right.Completely.
Weapon of Choice: His trademark weapon is a red crowbar he found in a tool kit at Black Mesa.
Alternatively, he's also depicted wielding a pump-action shotgun.
From Half-Life 2 onwards, the Gravity Gun.
Education: 2 years Martinson College, Undecided Major.
Employer and Position: Black Mesa Research Facility, Security Guard.
Clearance: Level 3.
Disaster Response Priorities: Preservation of research equipment and materials, welfare of personnel, and personal safety.
Voice Actor: Mike Shapiro (Half-Life 2 and Episode One)
The player character in Blue Shift, Barney Calhoun was a security guard at Black Mesa, and arrived to his duties at the same time as Gordon. Unlike Gordon and Adrian, he was the only player character in the first Half-Life not to have an HEV Suit, and the only main character to escape from Black Mesa on his own, along with a few scientists.In Half-Life 2, Barney, posing as a Combine Civil Protection security guard, saves Gordon from heading to Nova Prospekt. Helps Gordon in the Resistance movement in City 17, and for Episode One, helps some of the residents evacuate. Last seen boarding a train outbound from City 17 by the end of Episode One with the help of Gordon and Alyx, his whereabouts are unknown in Episode Two.
Also, the subtitles censor a different portion of the word "fuck" than is covered by the audible crash.
Put on a Bus: More accurately, the second-to-last train to leave City 17 at the end Episode One.
Reverse Mole: Works within the Civil Protection and uses it as a means to help civilians escape from the city
Rebel Leader: He seems to be the rebels de facto field commander, behind in rank only to Eli and maybe Gordon.
Took a Level in Badass: Barney handles himself well in Blue Shift (even surviving through Xen, for one), but when we meet up with him in the second game, he's one of the leaders of the Resistance, their mole in Civil Protection, and once the revolution hits the streets, a competent field commander.
Corporal Adrian Shephard
Training: United States Marine Corps, Special Forces.
Assignment: Hazardous Environment Combat Unit, Santiago, Arizona.
The player character in Opposing Force, Adrian Shephard was one of the men in his unit assigned to Black Mesa to do a full containment, cleaning out the witnesses, and finding Gordon Freeman. However, his transport was ambushed and shot down before he was given his mission, which leads him to work together with Black Mesa's scientists and security guards despite them becoming increasingly distrustful of him as the game progresses. In some of his attempts to escape and regroup with any members of his team, the G-Man both helped and hindered him along the way.He was ultimately detained by the G-Man in Another Dimension at the end of Opposing Force, now pending further evaluation.
Badass: Well, he is a highly trained marine with the best equipment that his unit can provide, but he still is way better at fighting than the other soldiers.
The Faceless: Has only two character art pictures of him, both with his gas mask on. His multiplayer image is just a generic HECU soldier.
Long Bus Trip: Despite the facts that Opposing Force ends with Shephard in in a state from which he could easily be brought back, and Gabe Newell himself have stated that Valve is planning to "bring him back one of these days", no mentioning of him has been made in any of the Half-Life sequels.
You Remind Me of X: G-Man uses variant 1 towards Shephard, and mentions his ability to survive against all odds as the main reason. G-Man also mentions that this why he saved Shepard's life and argued against his employers' wishes to kill him.
Employer and Position: Black Mesa Research Facility, Research Associate and Hazardous Environment Supervisor.
Education: PhD in Applied Physics, Caltech.
Clearance: Level 4.
Voice Actor: Kathy Levin
Dr. Gina Cross is one half of the protagonist team in Half-Life: Decay and a Black Mesa scientist. What happened to her after the events of Decay is unknown.
Armor Is Useless: See Made of Iron; bizarrely enough, she can survive much more damage than other human NPCs (bar Barney and Freeman himself), even though she's not wearing any kind of armor, just a jacket and hoodie.
Badass in Distress: In the initial Half-Life 2, she gets bagged by the Combine during the revolt, and almost ends up sent through a Combine portal before Mossman saves her. In Episode Two, she gets skewered by a Hunter and is rendered Only Mostly Dead until the Vorts save her.
But Not Too Black: Noticeably fairer-skinned than her father, commonly mistaken for a tanned Caucasian woman (even though she's half African-American, half Malaysian). In discussions praising notable People of Color in video games, she tends to get left off the list as a result.
Disney Death: In Half-Life 2: Episode Two she gets stabbed in the back by a Hunter, and just manages to say "Gordon... Help...." before she passes out, appearing to be dead. Her condition goes from critically injured to no pulse left just before the Vortigaunts manage to save her.
Breen:[to Eli] Will you let your stubborn short-sightedness doom the entire species, or...[touching Alyx's face]...will you give your child the chance her mother never had? She spits in his face. Alyx: How dare you even mention her!
Trauma Conga Line: Where to start? For the first years of her life, she lives in the dormitories of Black Mesa, a dangerous and accident-prone research facility. Then, her mother is killed during the Black Mesa Incident. She only survives because the G-Man saves her life, putting her in his debt unknowingly. Fast forward to when she meets Gordon Freeman, leading to events in which her father is captured by the Combine. In the end, when the dark matter reactor explodes, killing Breen, she only survives because the Vortigaunts teleport her out of the wreckage. In the beginning of Episode Two, she is stabbed twice by the long blades of a Hunter and survives, once again, because of the Vortigaunts. Finally, after Eli, Magnusson, and Kleiner launch the rocket and Gordon and Alyx are about to get into a helicopter to save their friend Mossman, a pair of Advisors smash through the building and kill Eli right in front of her.
What a Piece of Junk: Consider him a junky old robot at your own peril if you're a Combine. He will thrash you.
Dr. Isaac Kleiner
Voice Actor: Harry S. Robins (Half-Life 2, Episodes One and Two)
A major character in Half-Life 2, Isaac was the man who recommended Gordon Freeman to Black Mesa Research Facility's Civilian Recruitment Division. Also a survivor of the Resonance Cascade incident at Black Mesa. Was also Gordon's theoretical physics teacher at the Massachusetts Institute of Technology.
The other scientist at Black Mesa East, and is somewhat distrustful of Alyx. Also played traitor for Wallace Breen, but after coming back to her senses, she eventually saves Gordon, Alyx, and Eli from him near the end of Half-Life 2. Was last seen with Resistance members tracking down the Borealis, and got ambushed from the Combine before she could finish her message. She is still alive, whereabouts unknown. Her message was found by Gordon and Alyx, who were pursued by the Combine for the entirety of Episodes One and Two while delivering it to the scientists in White Forest Base. She will be most likely seen again in Half-Life 3.
The manager of White Forest Base. Has a very distrustful relationship with Isaac Kleiner (well, they fought between each other for grant money). Later revealed to be the owner of a certain microwave casserole in the lounge of the Sector C Personnel Facilities in Black Mesa.
Brick Joke: Remember the casserole you had the option to blow up in the beginning of the first game? According to canon, that just so happened to be Arne's casserole, and Gordon did in fact blow it up, something Arne still hasn't forgiven.
Evil Laugh: His laugh is pretty evil sounding, even though he's helping you.
Good Samaritan: Grigori is the only NPC in the entire game to help Gordon Freeman without recognizing who he is. He just thinks it's the right thing to do.
Good Shepherd: While there are few people left in Ravenholm for him to help, he gives Gordon a shotgun, some supplies, and has built several traps that Gordon uses on the zombies. It is implied that Grigori has done the same for other rebels.
A somewhat suspicious and supposedly British Resistance colonel, leading the New Little Odessa base along the coast. He only appears briefly in the 7th chapter of Half-Life 2, granting Gordon a rocket launcher.
Call Back: After playing out his minor role in Half-Life 2, he disappears from the plot, and there is no mention of him again. Then, late in Episode One, three independent mentions suddenly turns up concerning him, first Alyx sarcastically claiming he is her father, then two rebels coming to the conclusion that he is an idiot, and finally a rebel who reveals that he had taken the credit for Gordon's work, and who turns out to be an admirer of him.
Cower Power: When the base he has responsibility to lead comes under an attack threatening its very existence, no less, Cubbage sends Freeman to dispatch the gunship, while he safely hides to send a warning to another base, that mysteriously never reaches its destination.
Small Name, Big Ego: It is staggeringly clear that he believes himself to be one of the great heroes of La Résistance, although he appears to be the only one with this view, apart from one rebel in Episode One speaking somewhat highly of him.
Griggs and Sheckley
A pair of resistance members in an underground base, they help Freeman defend the base against an army of Antlions to protect the Vortigaunts while they heal Alyx.
Badass: Sort of. They are just normal resistance members, but they perform surprisingly well against the army of antlions.
Voice Actor: Mike Shapiro (Half-Life 1 and 2, Episodes One and Two)
A strange character, looking like a blend between a government worker and a businessman, who apparently has some limited control over space and time. All we know is that he's been observing the events of the entire Half-Life series. And that he is possibly not entirely human. He apparently answers to some higher authority which he simply refers to as his "employers". He has, however, on a couple of occasions hinted that he does not necessarily obey these "employers".
Affably Evil: We actually don't know how much "evil" he is. But if he is, he's pretty damn proper about it.
Ambiguously Evil: On one hand, his chessmaster antics, creepy dialogue, and mysterious powers make him easy to see as a villain of some sort. Plus, the Vortigaunts seem to oppose him and Eli suggests he's the one who gave Black Mesa the crystal that caused the resonance cascade in the first Half-Life. On the other hand, we know absolutely nothing about who he actually is and what his motivations are, and he seems to oppose the Combine, who actually are villains, and he has saved Freeman and Shephard's lives on several occasions.
The Chessmaster: Although no one even knows what he is trying to accomplish.
Children Are a Waste: The G-Man seems to disagree, as he saved Alyx Vance despite objections from his employers, presumably because he anticipated the role she'd play in the future. They didn't want him to, because "she was a mere child, and of no practical use to anyone." Well...how about now?
Consummate Liar: If the Nihilanth is to be trusted (which is a dubious condition, to be sure).
Nihilanth: Deceive you... he will deceive you...
Graceful Loser: Not necessarily a villain, but when the Vortigaunts foil some plan he has for Gordon, he is annoyed but doesn't retaliate; he simply waits for another opportunity to make contact, and does not seem to hold any kind of grudge against them for their interference.
Humanoid Abomination: Maybe. Standing still, he looks human. When he moves — and where he appears — tells you that he cannot be.
Inexplicably Awesome: One of the most intriguing parts of the G-Man is how little we know about anything about him, including how he does what he does, what he is, who he works for, and what he wants.
Invisible to Normals: He can apparently choose which persons are able to see him, and it is hinted that he also has some power over if they remember him or not afterwards.
I See Them Too: The G-Man appears to be invisible to everyone but Freeman and Shepherd at times. However, the Nihilanth, Eli Vance, and the Vortigaunts are all also aware of his existence.
Lack of Empathy: Debatable. He saves Gordon's life quite a few times and later he admits he saved Alyx and her family during the Black Mesa disaster suggesting that maybe he's capable of mercy. He also mentions to Shepard that he saved his life specifically because he sees him as a kindred spirit.
Manipulative Bastard: From locking out Gordon and Adrian from certain doors, to shoving them in deep-freeze, yeah.
The Men in Black: Doesn't quite fit the trope, but sure as hell evokes the basic concept, probably deliberately.
No Name Given: While he is called "G-Man" in the credits and character models, he is never actually referred to as this in-story. The only direct reference to him is Eli's label of "our mutual friend." As such, G-Man is not his actual name or even an In-Series Nickname.
Offscreen Teleportation: Though there are two scenes where you get to see him do it: Once in Half-Life ("Lambda Core"), and once in Opposing Force ("Foxtrot Uniform"). Though he has also appeared to Gordon literally out of thin air without using a visible portal, so...
Reality Warper: Can casually stop time and plant subliminal orders into people.
Voice Actor: Robert Culp (Half-Life 2, cameo in Episode One)
Breen is the earlier head of The Black Mesa Research Facility, and was unnamed and unseen in the first game, where he is merely referred to as "The administrator". In Half-Life 2, he is the main antagonist and the Combine's puppet ruler of Earth, a position he got after selling out mankind to them.
Affably Evil: Breen's pretty well spoken and calm for being a smug backstabber.
Breen: I'd like to take a moment to address you directly, Dr. Freeman. Yes, I'm talking to you. The so-called One Free Man. I have a question for you. How could you have thrown it all away? It staggers the mind. A man of science, with the ability to sway reactionary and fearful minds toward the truth choosing instead to embark on a path of ignorance and decay. Make no mistake, Dr. Freeman. This is not a scientific revolution you have sparked...this is death and finality. You have plunged humanity into freefall. Even if you offered your surrender now, I cannot guarantee that our benefactors would accept it. At the moment, I fear they have begun to look upon even me with suspicion. So much for serving as humanity's representative. Help me win back their trust, Dr. Freeman. Surrender while you still can. Help ensure that humanity's trust in you is not misguided. Do what is right, Dr. Freeman. Serve mankind. ''
Corrupt Corporate Executive: He was the administrator of Black Mesa before becoming the Combine governor of the Earth, and pushed for the risky analysis that eventually led to the disaster in the first game.
Misanthrope Supreme: His motivations are a wee bit unclear. He did convince The Combine to enslave rather than exterminate humanity (and was afterwards named Administrator of Earth), but whether he did so for personal power, or because he really cared about humanity is left unclear.
Narcissist: He's got propaganda posters of himself in City 17 and even busts of himself in some locations. Then there's the fact he's jumbo screens of him talking plastered all over the place.
Never Found the Body: We never really know what happened to him after the end of HL2 when The Citadel is destroyed.
Smug Snake: Things escalate beyond his control rather quickly.
Villainous Breakdown: He becomes increasingly impatient and childish as Gordon Freeman kills off his soldiers and starts a rebellion. When Gordon invades the Citadel, Breen goes from first trying browbeating him into surrendering, to franticly, but still condescendingly trying to reason with him, and finally he starts outright begging for him to stop.
A powerful trans-dimensional alien empire, they conquered the Earth and are the main antagonists in Half Life 2 and its episodes, as well as the whole series, as the Nihilanth was on the run from them. Their occupation force on Earth, the Overwatch, consists of a portion of their transhuman forces (modified humans using human vehicles and weapons), and "Synths", aliens who have been modified and outfitted with cyborg attachments and pulse weaponry.
Artificial Brilliance: None of the Combine forces are stupid. The Overwatch soldiers will flank, throw grenades, and run to cover when reloading, the Hunters will use splash damage, flank, and lay down suppression fire, and the Gunships will wildly strafe while firing, and will even shoot down your missiles in mid-air. Foot-soldiers, however, do not have a high amount of hit points, and will usually get killed by the player before their strategies can kick in.
Authority Equals Asskicking: The Combine Advisors are the top tier in the Combine hierarchy, or very close to it; they have the authority to subsume any Combine forces they need, and sacrifice them without a second thought. While they resemble blind limbless grubs the size of baby elephants, they have powerful telekinetic and telepathic abilities, and are able to completely immobilize and control anyone around them, as well as levitate themselves for transport.
They are also Made of Iron. You actually briefly get a chance to shoot at one during the first stage of the assault at White Forest, using a mounted pulse cannon, which seems to be the Combine's equivalent to a .50 machine gun. Desptie taking many shots, only a few of which are enough to kill Powered Armor wearing cyborgs, the Advisor shows no visible signs of injury and escapes unharmed. This also shows the limits of their powers; the Advisor can't actually throw Freeman around like the previous ones did, only being able to give him a headache, likely because of the (not at all long) distance between them.
Big Bad: Of the second game and subsequent episodes.
Bigger Bad: Of the first game. Also in Half-Life 2, while Breen acts as the Big Bad, the Advisors are clearly above him and are seemingly the Combine's leaders.
Les Collaborateurs: The Civil Protection members are humans who willingly decided to work with the Combines.
Creative Sterility: For all their advanced technology, The Combine Empire appears to be chronically unable to create something that is truly their own, original design. Every bit of their technology and utilities appears to have conceived by violently appropriating an already existing design from another race and then building upon, or rather twisting it until it serves the purpose they need it for.
The Empire: Possibly the best example. Most fictional empires would be satisfied with taking over the world or, at most, the galaxy. The Combine instead conquered the entire universe. But then, even that wasn't enough, so they made portals to other universes and proceeded to conquer them too.
Fake Ultimate Mook: The Combine Overwatch may look big and scary, but the untrained rag tag rebels are actually better shots (strangely this only applies to SMG's, rebels and combine soldiers are on par in accuracy with the other weapons). The Overwatch soldiers are actually more effective in combat though because of their ability to throw grenades and their slightly larger amount of health.
Foreshadowing: At the very least, something much nastier than the Xenians was hinted at by the Nihilanth way back in the first game.
Nihilanth: Their slaves...we are their slaves...we are...
Gas Mask Mooks: Justified, in that Overwatch Transhuman troops are in use on other, non-human-habitable planets.
Apparently the Civil Protection officers just wear them because it looks intimidating. Also Justified; this is something SWAT teams do in real life. Besides, given how brutal the metrocops are, it's probably best they remain faceless and anonymous.
Insignificant Little Blue Planet: It's clear that they don't give two shits about Earth or the humans, considering the token force they've left to occupy it (with the majority of even the transhuman forces being used elsewhere) and the state of the planet after they're done draining it for resources. They've conquered millions of species, the humans are just one more to them.
On the other hand, once they learn that the Rebels have developed simple and cheap teleportation (compared to the Combine teleporters at least), the Combine becomes immensely more interested in their activities.
Load-Bearing Boss: A collective, in-story version. For all the Combine's cruelty, they at least did manage to keep the massive Antlion infestations in check and keep headcrabs out of their cities. But then Gordon Freeman blew up Nova Prospekt, destroyed their defensive network of machine gun bunkers and 'thumpers' on the coast (thereby letting the Antlions into Nova Prospekt), slaughtered hundreds of soldiers and Synths, started a worldwide rebellion, and blew up the Citadel. All these things caused the Combine to lose control over City 17, resulting in a massive invasion by the nearby Antlion colonies and an infestation of headcrab zombies. By the time Episode One begins, the entire region is caught in a four way struggle between the headcrab zombies, the antlion hordes, the Resistance, and the Combine.
Mecha-Mooks: The Earth Overwatch seems rather understaffed (likely due to most of the transhuman forces being shipped off-world), so make use of units like automated turrets, scanner drones, and manhacks to make up for it.
Multiversal Conqueror: According to Word of God, the Combine have already conquered several universes, enslaving their home species and forcibly modifying them for use as Synths. They're in the process of doing the same thing to Earth.
Planet Looters: It's very clear that the Combine have no long-term plans for Earth. They're visibly just taking every resource they can use (including the oceans, atmosphere, and some population) and shipping it off-world.
Police Brutality: Civil Protection; some of their terror-mongering acts include beating people for no reason, shooting people after they surrender and lining up innocent people on walls and using them for target practice in true Nazi-Gestapo-meets-Soviet-NKVD style. Think of them as a world-wide example of the Stanford Prison Experiment.
Putting on the Reich: The Civil Protection and Overwatch uniforms were based on Soviet and Nazi designs. This was more blatant in the original concept art.
Sesquipedalian Loquaciousness: Apparently as part of protocol, the Metrocops, Soldiers and even the OverwatchAnnouncer use medical jargon Newspeak to communicate. Alien intruders are "exogens", zombies are "necrotics", turrets are "sterilizers", soldiers are "stabilization delegates", Freeman, as Anticitizen One, is "malignant" and contact with him is a "staph infection". Troops are also routinely issued orders like "inoculate", "shield", "clamp" and "cauterize".
Slave Mooks: An entire army of them, most of the Combine soldiers you fight throughout Half Life 2 and its episodes are actually cybernetically modified and enslaved transhumans. Also, the "Striders" "Gunships" "Hunters" "Dropships" and "Synth Scanners" you see in-game are all enslaved aliens or biomachines. It's implied that there are millions of enslaved species. The vortigaunts may have been one of them, though they were later found to be enslaved by the Nihilanth. In fact, the Nihilanth's species' role in relation to the Combine is never really explained and neither is Race X's role.
Sufficiently Advanced Aliens/The Juggernaut: They curb-stomped the combined military might of every country on Earth in just seven hours. It took Dr. Breen to convince them not to exterminate every single human and settle for enslaving us instead.
Sociopathic Soldier: Surprisingly, not the Overwatch. They're just brainwashed slaves. No, the real sociopaths here are in Civil Protection, mentioned above in Police Brutality; the corps consists of humans who joined the The Combine's forces willingly, for perks like extra rations and sexual privileges. They appear to be somewhere between SWAT police and low-ranking soldiers. Their tasks are basically to instill fear in every citizen, and to brutally crack down on small resistance pockets. Their technology is notably a bit more primitive, as well. Where the Overwatch and Airwatch use Striders, Gunships and energy weapons, CP units make due with APCs, patrol helicopters and sub-machineguns.
Starfish Aliens: The creatures running the whole thing, called "Advisors", resemble rhino-sized brain-sucking grubs with no eyes, arms, legs or face. The developers deliberately wanted to invoke the image of a species that passed its Singularity a very long time ago. They rely on mechanical arms and eyes for manipulation, and anti-gravity packs for movement. Well, those and their near-unstoppabletelekinetic and telepathic abilities.
Suicidal Overconfidence: Part of their official policy. Any Overwatch soldier who fails and lives to report about it will receive "permanent off-world assignment". Their destination is likely not pleasant.
We Will Wear Armor in the Future: Averted with the transhuman Overwatch soldiers, who wear kevlar-like soft armor that resembles modern riot gear with what look likes protective inserts, in contrast to the standard Sci-Fi plate armor with Shoulders of Doom that most FPS soldier enemies tend to wear.
A mysterious alien race from the other dimension, they only appear in Opposing Force, where their invasion is repelled by Adrian Shepard and his men, and is finally ended when the US government nukes Black Mesa. Their main soldiers are "Shock Troopers", but they also have creatures such as a giant worm that shoots lasers and a small, fast poultry-like creature that attacks with scythe-like claws.
Shock and Awe: The aptly named "Shock Troopers", who carry a weapon called a "Shock Roach", a parasitic bug that shoots deadly electricity when squeezed. Also, the Voltigores, large creatures which shoots powerful bolts of purple electricity.
Shrouded in Myth: You don't learn much about them other than that they want to take Earth's resources and that they are hostile to Xenian and US Military forces.
Starfish Aliens: Especially the Gene Worm, a very large creature that shoots acid, and can teleport in "Shock Troopers". The manual for the game implies that the gene worm is several miles long and can suck the resources out of a planet, and that the creature you fight at the end of Opposing Force is just its head.
The ruler of the Xen aliens and the main antagonist of The first Half Life (and by extension, Blue Shift, Decay and part of Opposing Force). His race was under severe threat from the Combine, being hunted to near extinction. Some time prior to the first game, he enslaved the Vortigaunts, who were further pursued by the Combine. To escape them, he and the Vortigaunts fled to the border world, Xen, where they set up shop. Still desperate, he used the Resonance Cascade to launch an invasion of Earth, and despite the Black Mesa's scientists' best efforts to plug the rift between the dimensions, he was able to use his psychic powers to force it to stay open. His forces had success with pushing back the HECU, but his invasion was ended when the Black Ops nuked Black Mesa and Gordon Freeman traveled to Xen and killed him, finally closing the hole in the dimensions.
Ambiguously Evil: Mostly because we know so little about him; what we do know casts him in an ambiguous light. On one hand, he did enslave the Vortigaunts and invade Earth, with his forces being quite indiscriminate in their killings. On the other hand, the Black Mesa scientists had repeatedly invaded Xen to take apparently valuable crystals and specimens (including actually sentient soldiers in the Nihilanth's army), and Marc Laidlaw confirmed that the Nihilanth's invasion of Earth was largely an act of desperation, as his kind had been hunted to near extinction by the Combine. He also seems to care somewhat about Xen's ecosystem, given his apparent horror in the telepathic message he sends to Gordon after Gordon kills the headcrab queen ("'''Doooone... what have you dooooone?"), and was the only thing keeping the Combine from invading our universe.
Attack Its Weak Point: The only way Freeman can kill the Nihilanth is to fire everything he's got directly into its brain. Even then, it takes quite a bit of damage.
Authority Equals Asskicking: Just like the Combine Advisors, he leads a large army and has very powerful telekinetic powers, which include the ability to teleport himself and others, telepathy, the ability to shoot extremely powerful balls of lightning, and levitation. His commanders and possible relatives, the "Alien Controllers", also possess these abilities, but to much less powerful degrees.
Big Bad: Of the first game, and by extension, Decay and Blue Shift.
Black Eyes of Evil: His eyes appear plain black, unlike the other sapient Xenians, whose eyes are red. He may not even have eyes, just holes where they should be like the Stalkers, but it's hard to tell.
Body Horror: In addition to his general creepy anatomy, he also has what appears to be amputation scars on his chest, slave bracelets, and a mutilated legs that have been burned to vestigial stubs. But Marc Laidlaw denies that this is the result of being captured by the Combine, which is a common fan theory.
Fat Bastard: His torso looks a little more human-like than the other Xen aliens, making it somewhat noticeable that he looks overweight. This is likely the result of his legs being vestigial, and him floating around everywhere.
Flunky Boss: One of the more annoying parts about the fight with him. He'll launch a green orb that either teleports you to another room or spawns some vortigaunts or Alien controllers in his chamber. The second option isn't so bad, since he only spawns a few at a time, but him teleporting you to another room is very frustrating. In one instance, he'll teleport you to a room with a Gargantua, forcing you to have a boss fight in the middle of another boss fight.
Foreshadowing: His telepathic messages have a ton of this in regards to the Combine, the G-Man, Gordon, and possibly Breen and Shepherd.
Also one in-story; his psychic powers were the only thing keeping the portals between the Combine's universes and Xen closed. When he died, the Combine were free to pour through Xen, and then to Earth.
Large and in Charge: The largest alien ever encountered in the series in terms of pure size. Even bigger than the three story tall tentacle monsters.
Leaning on the Fourth Wall: Much like the G-Man and the Vortigaunts, most of his comments may be just as much about the player as they are about something in-universe, and open to many theories. For example, in the quote below, he is both the last of his kind, possibly the last thing keeping the Combine away from Earth, and the last boss.
Psychic Powers: The only psychic seen so far, aside from possibly the G-Man, who can affect things on a planetary scale. He was able to keep open a dimensional rift, telepathically mind control an entire species, and, judging by what happened after he died, was powerful enough to trigger disastrous portal storms all over the Earth, resulting in Xen wildlife killing off most of Earth's native fauna. Compared to that, his personal combat abilities (which are still formidable) seem rather unimpressive.
Puzzle Boss / Damage-Sponge Boss: To actually damage him, you need to find out that he is using the crystals to regenerate his force field and destroy the crystals. After that, his protective orbs won't regenerate, and he can be killed, but it takes quite a bit of damage.
Telepathy: He broadcasts telepathic messages to Freeman all throughout Xen, and can also use this ability to communicate with other Xen creatures.
Turns Red: Inverted. Throughout the battle with him, he will become progressively weaker as he gets injured until he finally just starts firing one ball of lightning at a time at you, as opposed to the dozens he fired before.
The HECU (Hazardous Environment Combat Unit)
The special forces unit who was sent to Black Mesa to clear up the aliens, it is soon discovered that they are also under orders to silence all the Black Mesa personnel...with bullets. They end up having to pull out, leaving behind dozens of their own troops in the process, while the Black Ops took over the operation.
Artificial Brilliance: They were praised as being the first tactically intellegent enemies in video games.
Band of Brothers: Subverted and played straight. Many soldiers throughout Opposing Force are shown to care for their squad mates, but the same can not be said for many other members of the unit, particularly the commanders, who abandon several dozen soldiers in their attempt to escape from Black Mesa in blatant violation of the "Never Leave a Man Behind" policy. In fact, two of the soldiers refuse to turn Gordon over to their bosses because they don't want to see him alive after he'd killed so many of their compatriots.
Cavalry Betrayal: You rather quickly find out that they are not at Black Mesa to help the employees and especially not Gordon.
Moral Myopia: Two soldiers that capture Gordon seemed rather outraged at him for killing so many soldiers, even though 100% of those guys were trying to kill Gordon.
Retcon: Originally, they were only called "soldiers" or "the military". They received their current name in Opposing Force. In the original Half-Life, their helicopters even had a US Army logo on them.
Given this, and some other facts (HECU grunts are recognized as marines, land vehicles have Army markings, the F16 is a plane used by the USAF) some fans have theorized that HECU is a multi-branch effort, like SOCOM in real life.
More Dakka: Many of their weapons, such as the M249 and Flash missile launcher. Hell, even their standard issue sub machine gun has a 50 round magazine.
The Engineer: He gets introduced in Opposing Force. While engineers are meant to fix vehicles, the engineer in Opposing Force is more useful for just opening locked doors with his blow torch and fighting with his Desert Eagle.
The Medic: Another class introduced in Opposing Force. While he isn't very effective with his Glock 17 handgun, he is the only thing in the game that can heal your teammates.
The Big Guy: Yet another class introduced in Opposing Force is a tall, muscular soldier toting an M249.
You All Look Familiar: They had exactly four models, which just changed the head: the caucasian officer who wore a beret, the normal mook who wore a gas mask, the shotgun using soldier who wore a balaclava and goggles, and the grenade launcher using African-American soldier who wore no hat or mask, and smoked a cigarette. The latter was changed to simply being an African-American version of the officer with a mustache in the HD pack.
A very shadowy unit sent to Black Mesa after the HECU failed their tasks, the Black Ops are there to remove everything in the facility, including the dozens of HECU stragglers left behind. In any way possible. Their purpose is only explained in Opposing Force.
Badass Army: See Elite Mooks. Also, the fact that they never make noise is pretty impressive when they're being shot constantly.
Elite Mooks: In addition to being completely silent, the male black ops they use powerful hand to hand moves at close range, run much faster than the marines, and have a little more health. The female black ops on the other hand prefer to flip and jump around wildly while pelting the player with pistol fire and kung-fu kicks.
Faceless Goons: They all wear balaclavas, and the female black ops also wear night vision goggles.
Hive Mind: Or at least an entire race somehow connected on a metaphysical level by the Vortessence. Whatever that is.
Magic by Any Other Name: They can shoot lightning, they can charge your suit, they can heal critically-injured Alyx, and power generators. And it's all just put down to "the Vortessence"
Not Always Evil: In the first game, they were typical Mooks for Gordon Freeman to mindlessly kill. It turns out, they were only fighting you because they were enslaved by the Nihilanth, and they help La Résistance in the second game and its episodes. Whoops.
One-Man Army: You didn't think that the humans were the only ones with these, did you?
X-8973 and R-4913, the two Vortigaunts from the Playstation 2 exclusive expansion, Half-Life: Decay. They are noticeably more durable than standard Vortigaunts, have stronger and seemingly more developed electrokinesis, and can regenerate health by damaging enemies. Something of a downplayed example though, as they work as a team and only get to take down twenty or so soldiers in the small bonus chapter in which they appear.
The three Vortigaunts in Episode 2 who slaughter dozens of antlions, turning what used to be a tough Hold the Line moment into a glorious Curb-Stomp Battle. The one that accompanies you throughout the mines, nicknamed the Victory Mine Vortigaunt, is probably the best example.
Starfish Aliens: They have at least four eyes. That seem to all be the same eye. Also, they have three arms, lightning powers, and some sort of Hive Mind (that may or may not overlap with the very (vort)essence of the universe).
Starfish Language: Vortigese and the related "flux-shifting" ranges from a 'normal' spoken language to telepathy to a language where two vortigaunts have to talk at the same time to properly communicate.
Super Strength: While it is not as pronounced as the strength of the Grunts, they still have it. The very first time you encounter one, it breaks down a 20mm thick heavy metal door with a few hits, with the door being reduced to pieces.
Took a Level in Badass: In the first game, they were disposable mooks, slaughtered in droves by Freeman and the soldiers. By Half-Life 2, they're much more powerful combatants (individually about on par with the original's Hard mode Vortigaunts) and have gained new mystical abilities including, at one point, resurrecting someone from the dead.
Parasitic alien lifeforms. Originally from an unknown dimension far from Xen, they were eventually brought there by the portal storms. After the Resonance Cascade and the following portal storms, the headcrabs migrated and set up shop on Earth. Their most notable quality is their ability to turn humans (and possibly other creatures) into Zombies by attaching to their heads.
Body Horror: For unknown reasons headcrabs mutilate a persons body, possibly because as a parasite they are draining its "resources". Standard Zombies have their ribcages open like teeth and their organs are on display. The bloodied faces of the victims aren't much better.
It gets worse with elite zombies. Fast Zombies look like all of the flesh save the bare muscle is gone and the poisonouis zombies have a smashed in looking "face" and a back that appears to have been eaten away.
Butt Monkey: In a way they are this, even if they are creepy. They are usually getting obliterated by both Combine and rebels and even the game actively encourages you to kill them in "creative" ways such as throwing saws, using traps, or setting them on fire. Of the four factions competing for control by the end of Half Life 2 they are probably the weakest, with their only saving grace being their sheer numbers.
Elite Mooks: In the first game, there were just basic headcrabs and zombies. The later games introduce new forms.
Opposing Force has the gonome, a mutated version of the standard headcrab zombie. Not only does it have more health than a normal zombie, but it can throw some sort of projectile and sprint.
Half Life 2 introduces the fast headcrabs and poison headcrabs, as well as their accompanying zombie forms.
Fate Worse than Death: Headcrab zombies can be heard crying out in pain, and playing their audio backwards reveals a large amount of dialogue such as "God Help Me! Help me!" or "Get it off me!" This heavily implies that headcrab victims are aware of what's happening but unfortunately there is no way to remove headcrabs without killing the victim.
Fragile Speedster: Fast headcrab zombies are the fastest ones by far, and are arguably the most dangerous for this reason. However, they have no more health than a standard zombie, and so are only a big threat in large numbers.
The Goomba: Both the zombies and the headcrabs themselves, with the former being almost a complete non-threat due to their slow speed, low health, and weak attacks, and the latter dying in one or two hits from just about anything and doing next to no damage.
Large, insect like creatures that migrated to Earth following the portal storms. They seem to operate much like many Earth insects, living in extremely large colonies with other antlions. After the events of Half Life 2, the street war between the Combine and the Resistance has caused a breakdown of the Combine defenses, and the antlions have started pouring in to civilized areas.
Cannon Fodder: Antlion soldiers. The most commonly encountered ones by far, they pretty much just charge and attempt to bite/claw whatever is threatening the colony with little regard for personal safety. Good thing they're extremely numerous.
Large, stationary creatures that wait on the ceiling for prey to wander in range, where upon they grab their prey with their tentacle and pull it up into their mouth.
Extreme Omnivore: They'll eat just about anything organic, from humans to antlions to birds. On the other hand, should they pick up something they cannot eat such as wood, they'll chew it a little, get frustrated and spit it out.
Neck Snap: How they instantly kill non player characters in the second game. Freeman is immune, possibly due to his HEV Suit.
One-Hit Kill: If they actually manage to bite you. Fortunately, this is ridiculously easy to avoid, to the point where you'd have to be trying to get eaten to actually get eaten.
Overly-Long Tongue: Weaponized, as they wait for prey to wander into their dangling tongues and drag them up to devour them.
The backbone of the Nihilanth's Xenian army in the first Half-Life. The Grunts are tall, bipedal, muscular creatures with multiple red eyes, backward jointed legs, tube ears, vertical opening mouths, and an arm sticking out of their chest, similar to the Vortigaunts. They make up a large part of the invasion force during the Black Mesa Incident, where the Nihilanth's forces squared off against the HECU.
Bee Bee Gun: Their weapon, the Hivehand, which shoots alien "thornets", which are less like bees, and more like flying, poisonous, heat seeking armor-piercing daggers of death that can find you anywhere
Cyborg: Their armor and weapons look like they are surgically grafted on to their bodies, and the Grunts themselves are artificially created in a factory.
Dumb Muscle: The Grunts only appear to be semi-sentient. They can operate weaponry, including their Hivehands and powerful alien laser cannons, and order around Vortigaunts, but not much else.
Elite Mooks: They're much more dangerous than the Vortigaunts/Alien Slaves, the other foot soldier of Xen in the first game, due to their high health, heat seeking projectiles, and armor.
No Sell: Shooting the armored parts of the Grunts will simply do no damage at all if you shoot them with a pistol, shotgun, assault rifle, or even an uncharged Tau Cannon. Oddly enough (and good for the player), their armor is placed just about everywhere but the Grunt's torso, the most likely place it is to get shot.
This isn't all they share; like the Controllers, they also have the Vortigaunts' red eyes, vertical opening mouths, backwards jointed legs, hoofed feet, bipedal posture, two legs, and claws (well, on their third arm at least).
Organic Technology: Their main weapon, the Hivehand, mentioned above, is a textbook case. This trope applies to the Grunts themselves, as they are a....
Servant Race: Towards the end of the game, you can find a factory run by Vortigaunts, with several barrels on an assembly line. Opening these barrels will reveal Alien Grunts- the implication being that the grunts are a manufactured species. This fits with the bio-technology theme of Xen.
Super Strength: In various scripted scenes, they're seen doing things like prying open steel doors with their bare hands, or punching marines through walls.
The tanks of the Xen forces. The Gargantua is a twenty foot tall blue creature with an armored shell, two vestigial arms, two functioning arms, and one large eye. Their main arms have pincers that can open to emit jets of blazing heat. They only appear a few times, but you will remember them.
Ambiguous Robots: Their seemingly metallic skin and built in weapons makes one wonder. They actually share a few traits with Combine synths.
Cyborg Possibly. It does look pretty mechanical. Special mention goes to its built in weapons, glowing machine-looking eye that changes colors, and armored metallic skin.
Death from Above: How one is taken out in Forget About Freeman; Freeman calls in an air strike on it, and the HECU aircraft, not knowing who sent the signal, are happy to oblige. Cue exploding Garg.
Made of Iron: Bullets just bounce harmlessly off their skin. It takes a TON of explosive or electrical damage to actually put them down, more than the actual M1 Abrams tanks in the game. Even more so in the modBlack Mesa (a recreation of Half Life 1 in HL2's engine), where there is absolutely no conventional way to kill them, even with all the explosives the player can carry; they can only be taken down with scripted sequences.
Mini-Boss: They serve this role whenever they appear in the original Half-Life; they're very tough, and half the time are meant to be taken down in scripted sequences to boot, but don't last as long and aren't as powerful as the actual bosses, of which there were only three (the Tentacle, the Gonarch, and the Nihilanth).
Natural Weapon: They can open their arms to release streams of fire/plasma/something that's powerful enough to actually reduce a human to Ludicrous Gibs rather than just burn them. They're also fond of simply crushing their enemies, or shooting a weird energy beam by stomping on the ground that can seek out targets and, again, gib them.
One-Scene Wonder: When they appear; they are always solo. Pretty straight forward in Opposing Force however, where only one total Gargantua appears in the game; stuck in demolation cables on the hydro-electric dam.
Walking Tank: Notable because they actually resemble a giant version of the primary Xenian heavy infantry unit, the Alien Grunt. Both are bipedal, both have backwards jointed legs, hoofed feat, red eyes, multiple sharp teeth, and two arms ending in weird hand-less ends that open up. See◊ for◊ yourself.◊ This the only real hint we get it in-game that they're part of the Xenian military rather than just wild animals... well, that and the fact that they don't attack sentient Xenians the few times its possible to get Gargs and Vortigaunts in the same room. The same doesn't apply for Xenian wildlife.
Made of Iron: Despite being squishy looking, Controllers can take more damage than even the fully armored HECU soldiers, and much more than the Vortigaunts. This is likely because they have a weaker, invisible version of the Nihilanth's psychic shield, as they share many other abilities with him and do not visually wear any armor.
Mini Mook: They resemble the Nihilanth in many ways, but according to the Nihilanth himself, they're not of the same species. They look like hybrids of Nihilanth and vortigaunt, so maybe they're an artificial crossbreed species.
Mook Lieutenant: According to Laidlaw, the Controllers are basically conduits for the Nihilanth's psychic control of the Vortigaunts, and as a result are the highest ranked "generic" aliens on Xen.
BFG: The powerful energy weapon they have built into their bellies, which in various scripted sequences is seen doing stuff like disintegrating rather thick rock formations and reducing an Osprey to scrap in less than a second of sustained fire.
Gentle Giant: When encountered on Xen, they're completely harmless, and are pretty much the only moving thing that WON'T attack you. On Earth, however, they act as a dropship for the Xenian forces and attack HECU aircraft.
Lightning Bruiser: Can take as much damage as a tank and fly at speeds that at least exceed Mach 1, evidenced by the shock waves they create.
Made of Iron: You only actually fight one once, at the end of Decay. It takes as much damage as a tank to put down, though that may just be its Final Boss-ness in action.
Natural Weapon: A laser-like weapon built into their belly that they can fire downward. It bares some resemblance to the weapon used by Combine Gunships when spawned by the console.