In Half-Life 2, you’re going to have to murder a lot of hostile beings in order to save the day. Make sure to read up on these nasties or you may end up as lunch, or worse...

Headcrab Hostile Xen Wildlife These ferocious little crustaceans have returned from the original game. Essentially the same creature, headcrabs have evolved since the we first saw them, now coming in Fast and Poison varieties. They no longer simply wait in tunnels to spring out at you, Headcrabs are found everywhere, and have even overtaken the village of Ravenholm, being used as a biological weapon by the Combine and launched into populated areas.

Zombie Headcrab Victim Zombies are back, with some new tricks. Killing the host body does not mean the headcrab is dead, so aim for the head. Also, they now can get chopped in half, and their upper torso will continue to crawl after you. There are also as many varieties of zombie as there are headcrab now, each with it's own unique new attacks.

Barnacle Hostile Xen Wildlife Always hungry, and nearly everywhere, the Barnacle is also back from Black Mesa. The sewers of City 17 are crawling with these nasty, pulsating mouths. They will try to eat anything (literally), and will grab birds, barrels, Combine or anything else that touches their tentacle.

Fast Headcrab Hostile Xen Wildlife Spindly and almost spider like, the fast headcrabs are hyperactive cousins to the regular ones. They move very quickly and attack viciously and repeatedly. While they don’t cause more damage per attack than the regular ones, they attack more often, and are harder to hit, so present a bigger threat.

Poison Headcrab Hostile Xen Wildlife Poison headcrabs are big, slow and ponderous, but don’t let that fool you into thinking they aren’t dangerous. Poison headcrabs can not kill you, but they bring you down to 1 health in a single attack, making you easy picking for anything nearby. Your HEV will administer an antidote for the poison, but you will be vulnerable until you are back to your previous health.

Fast Zombie Fast Headcrab Victim Fast zombies are the result of a fast headcrab infestation. They are skinny, and their corpses have been stripped of all of their skin, leaving bundles of exposed muscle. They scream in pain as they attack, climbing drainpipes and smashing through windows to get at their prey.

Poison Zombie Poison Headcrab Victim Poison zombies are even slower than their headcrab makers. They usually carry 1 to 4 additional poison headcrabs with them, and can absorb insane amounts of damage before dying. It is suggested that you use fire if at all possible to kill the zombie and its passengers.

Antlion Hostile Xen Wildlife Antlions are a complex life forms from Xen. They live in colonies, and are sensitive to movement on the ground above them (think the movie "Tremors"). They will burst out of the sand and attack anything on the surface that moves. Keeping to rocks and high-ground is a good idea if you know antlions are around, since there is an endless supply, and you will run out of ammo (and life) before you run out of antlions. Pheropods make them your willing slaves.

Leech Hostile Xen Wildlife Another fond memory of Black Mesa were the hundreds of tiny leeches chewing on your butt when you were underwater. Well, now they have bred in the millions in the world’s oceans, and they want the whole meal. Stay out of coastal waters or your life will be measured in seconds.

Civil Protection (Metro Cop) City 17 Police CP are the city soldiers of the Combine. Their job is to bully the general populace and intimidate them into supplication. They don’t carry very powerful weapons, mostly pistols and MP7s, but they also carry manhacks, and usually travel in groups. They are the easiest Combine to kill.

Combine Soldier Combine-Assimilated Human Being Patrolling the outskirts of City 17 and running Nova Prospekt are the Combine Soldiers. They carry Pulse Rifles, MP7s and Shotguns, and are more than happy to flush you out with grenades in order to make you an easy target. While they are harder to kill then Civil Protection, they are easy enough to kill with a shotgun or grenade. Rarely they may also be hiding in sniper nests and equipped with laser-sighted sniper rifles. In this case, use cover to your advantage and toss a grenade into their nest.

Scanner (Type 1) Combine Surveillance Robot The basic scanner is an annoyance at best, following you around and occasionally blinding you with its camera flash. Take them out as convenient, but be careful to finish the job once you start; they ram and explode if they take enough damage.

Scanner (Type 2) Combine Surveillance Robot The next step up from the basic scanner can be seen dropping hopper mines into battle or using their light machine guns in addition to their typical follow and annoy role.

Manhack Combine Eradication Robot "Flying Blades of Doom" is an apt name for these. Manhacks are small robots that hover around with spinning blades, attacking any non-Combine they find. They are little more than a distraction on their own, going down relatively easily with a crowbar or pistol, but can be dangerous in groups. The gravity gun makes them less threatening, and they can even be used like an old-school Doom chainsaw in this fashion.

Roller Mine Combine Explosive Think of them as steel soccer balls that chase and electrocute you. Rollermines are magnetic and will attach themselves to any enemy vehicles they come across, or just pummel and electrocute any poor bastard caught on their own. They react badly to explosives and water, and can be used effectively as weapons with the gravity gun.

Hopper Mine Combine Explosive The "Bouncing Betty" of HL2. Hopper mines sit stationary until something comes near, depending on it's setting. When set off, they jump to just over head level and explode. Hopper mines clamp their claws into the ground to hold themselves in place, making them difficult to pick up. When launched by the gravity gun, they explode on impact.

Combine Elite Combine-Assimilated Human Being The Combine Elite soldiers are smarter, tougher and better armed than their normal brethren. They often carry Pulse Rifles, armed with the plasma grenade secondary fire mode. If they weren’t tough enough on their own, they often travel in groups with other elite and Combine soldiers.

Turret Combine Defense These sentry guns are set up in defensible positions throughout Nova Prospekt and City 17. They are completely automated and attack any non-Combine that passes by them. They can be reprogrammed to attack their creators, which is an essential tactic at many points in the game.

Bunker Turret Combine Defense Located in the City 17 City hall, these guns are built into the floors. When they are tripped (usually by laser tripwire) they rise out of the floor and begin scanning the area with a laser finder. If it detects a target, it immediately begins firing. They are almost impervious to anything but grenades.

Combine APC Combine Vehicle Usually found sitting still, being used as power supplies or blockades, APCs are sometimes encountered during battles. They fire a pulse rifle at closer targets, but can also unleash a hail of rockets if the target is too far away.

Antlion Guard Hostile Xen Wildlife These are the big brothers to the basic antlion. They have massive, battering ram like heads that they use to smash anything non-antlion into oblivion. Since they carry pheropods themselves, antlion guards do not care if you are carrying them and will flatten you regardless. They are big bugs that will squish you like a person.

Icthyosaur Hostile Xen Wildlife Only briefly seen in HL2, the ichthyosaur was a very tough adversary in the original game. They have apparently spread to many lakes since Black Mesa.

Hunter-Chopper Combine Vehicle Tough, fast and maneuverable, these vehicles are the bane of the middle of HL2. They drop in from out of nowhere, and attack with pulse rifle fire and by dropping timed explosives. On the plus side, the choppers have to be facing you to shoot you.

Combine Gunship Combine Synth Think of them as living, breathing helicopters. They are faster and more maneuverable than the standard hunter helicopters. They are also more aggressive, and growl intimidatingly when angered. Fortunately, your friend the RPG can take them down. Unfortunately, they can shoot the rockets out of the air.

Strider Combine Synth Striders are kind of like a walking version of the gunship. They are smart and tough. They carry a pulse gun, but also have a powerful dark energy weapon that warps the space around the strider when it fires, and is devastatingly powerful, capable of destroying buildings and killing anyone in a single shot.

Combine Dropship Combine Synth Drop ships are the main mode of transportation for Combine troops. They are extremely tough, being impossible to shoot down. Of course, they are armed with a pulse rifle which covers the exit of any Combine Soldiers. If fighting against one, avoid the gun and kill the soldiers leaving it. The crate carried by the drop ship can be destroyed if hit by enough rockets.

Dr. Wallace Breen (The Administrator) Combine/Earth Laison Dr. Wallace Breen was Black Mesa's administrator and he is a traitor to mankind, helping the Combine to take over the world and assuring himself a ritzy penthouse apartment in the Citadel.