Threat: Minimal
Speed: Slow

A smaller Xen creature found in small water pools across Black Mesa, this creature feeds off HEV suit energy. Its small size makes it hard to hit with bullets or any other weapon, but a crowbar can easily deal with them. The only danger is when dealing with large groups.

Threat: Medium
Speed: Fast

An organic weapon, Snarks were believed to be developed by the Xen forces to be used against Humans.

These creatures remain domant, until disturbed by the smell of flesh or set on a prey. After waking, they run for their prey and attack them with powerful jaws. They never give up the chase, and will kill any creature that is unable to kill or outrun them. Fortunately, after 20 or so seconds, the snarks short life will come to a end and the creature explodes in a shower of acid.

Threat: Low
Speed: Medium

The foetal stage of the headcrab, this creature is smaller, slightly translucent and weaker. This makes the Baby Headcrab not as much of a threat as other monsters, but a large number of Baby Headcrabs can overwhelm a opponent.

Threat: Low
Speed: Medium

Threat: Low
Speed: Slow

The Zombie is known to take on multiple forms. They can have Human Grunt, Scientist, or Security Guard host bodies. They feature two slash attacks but no long range attack. They are ideally attacked with a crowbar.

Threat: Low
Speed: N/A

These cave-dwelling creatures attach themselves to a ceiling and wait for food to run into its long tongue. Once its prey has been pulled up to its mouth, it chews and digests them quickly. Despite this slow but powerful attack, it has low health and drops any prey on death. If you are unfortunate to run into a tongue, kill the barnacle as soon as possible.

Threat: Moderate
Speed: Medium

These dog-like creatures have no melee or long-range attack, instead they charge up and use a sound-based attack that kills nearby enemies. This attack can hit multiple targets at once, but if the Houndeye is hurt while charging its attack, then it is interrupted. These creatures work as packs and their attacks do not affect each other.

Threat: Moderate
Speed: Medium

A competitive creature found near the liquid pools of Xen, the Bullsquid�s natural prey is the headcrab. Highly territorial creatures, they attack any other bullsquid that they see on sight. The Bullsquid's acid attack, although long-ranged and inaccurate, can be extremely damaging close-up. In addition, the bullsquid has a powerful melee attack that can throw players long distances.

Threat: Moderate
Speed: Medium

Threat: Moderate/High
Speed: Medium/Slow

Threat: Moderate/High
Speed: Medium

These flying monsters are responsible for controlling the Alien Slaves on Xen due to their high mental ability. With their flying ability, they have no need for melee attacks and instead use the power of their mind to launch balls of energy at and enemy. A variation of their primary attack is a slower, larger ball that follows its target.

Threat: High
Speed: Fast

Zombies that were not eliminated by the Military or by Freeman hid themselves away in the dark depths of Black Mesa to continue their gestation, becoming the Gonome within a few hours.

The gonome has lot less human features than the zombie, including a strong exoskeleton, a more muscular build, and a large mouth in the center of its torso. The Gonome is faster, stronger and smarter than the zombie, and is a much larger threat as a result.

As well as strong melee attacks, the gonome can also throw acidic spit, similar to the Bullsquid, that can burn through skin and armor. 

Threat: V. High
Speed: Fast

Although not anywhere near as dangerous as the Garg, these monsters still present a threat to a unaware player. The Baby Garg has yet to finish developing a hardened exoskeleton, which makes it vulnerable to projectiles. Explosives however, are the best bet for taking the Baby Garg down quick!

Threat: Extremely High
Speed: Fast

Threat: Very High
Speed: Fast

Even more resistant to damage than the Gargantua, the Tentacles need to be exposed to a high level of heat in order to be destroyed.

Threat: Low
Speed: Medium

Threat: Medium
Speed: Fast

The creatures main attack is an ability to fire a number of armour piercing spikes accurately at long range. Also, the Pit Drone can cause serious damage with its two front arms if a target is unlucky enough to face them at close range.

Threat: High
Speed: Fast

The brains of Black Mesa, the scientists are useful in some situations. They can open doors and even heal you if your health is below 50%. They will follow you in most situations. However, if an enemy is near or you run too fast, they will either run away or stop following you immediately.

One half of Black Mesa's security force before the incident, these effective guards carry a 9mm handgun and a weak form of body armor. They can also escort players and provide cover when necessary.

Barney can also open up some secured doors and area's, allowing you to advance or to gain extra goodies. If you find a door you can't open with a retina scanner, bets are that you need barney or one of his buddies to open the door for you. 

Fat, dumb and slow, Otis makes up for it with his Desert Eagle and high accuracy. Like Barney, Otis is generally friendly and can provide effective cover. 

Threat: Medium
Speed: Fast

Brought in to assist in missions too classified for the standard grunts, these Assassins are both fast and deadly. The silenced 9mm pistol they carry has a fast rate of fire and is highly accurate which makes these among the most dangerous enemies you can encounter.

This Grunt carries the standard MP5, a submachine gun and a competent long-range weapon, as well as a number of Hand Grenades.

Threat: Medium
Speed: Fast

This Grunt carries a shotgun, dangerous at close range, as well as a number of Hand Grenades.

This Grunt carries the standard MP5, a submachine gun but also has the added danger of a mounted Grenade launcher which fires powerful contact grenades.

The Leader may be armed with any Human Grunt weapon. He is very valuable because he relays information to his squad on an enemy location. If one spots you, you will find a whole squad closing in on you and your teammates location.

The Heavy Weapons Grunt is armed with a chain gun. It takes a short amount of time for their chain gun to spin up. They are very slow, but their chain gun will kill an enemy such as a security guard or player in a few seconds. 

Playing a major role in the Black Mesa clear-up. These special forces entered combat after the pull-out of the majority of the military forces. Faster, more accurate, and deadlier than your average Grunt, these forces are a major threat.

The MP5 assassin can carry either a standard MP5 or an MP5 equipped with grenade launcher 

Playing a major role in the Black Mesa clear-up. These special forces entered combat after the pull-out of the majority of the military forces. Faster, more accurate, and deadlier than your average Grunt, these forces are a major threat.

The Martial Arts Assassin does not carry any weapon, but is highly trained in melee combat. If they can get close enough to their target, they can take them down quick. 

Playing a major role in the Black Mesa clear-up. These special forces entered combat after the pull-out of the majority of the military forces. Faster, more accurate, and deadlier than your average Grunt, these forces are a major threat.

Assassins armed with a Sniper Rifle should be eliminated on sight. Their Rifle can pierce both HEV and PCV armour with little resistance. 

Sentry Turrets are usually found near Human Grunt emplacements. They are built by Human Grunts. If they hear a sound or if they are damaged, they will activate immediately. If one becomes active, many nearby sentry turrets will also become active.

The Mini Turret detects, deploys, and attacks a target at a fast rate. Originally built for Black Mesa's security, these machines have been tampered with and are now under military control. They will not attack Human Grunts.

The larger version of the Mini Turret, these machines are armed with a massive chain gun. Originally built for Black Mesa's security, these machines have been tampered with and are now under military control. They will not attack Human Grunts. When an enemy is detected, it will take about 3 seconds for them to deploy and start up their chain gun. When they are active, they will eat up almost any enemy in a matter of seconds.

While not deployed during the Black Mesa incident, these prototype units are one of the more effective military forces. While featuring similar weaponry and abilities as the Human grunts, the strong armor of the Robo Grunts makes them resistant to most weaponry and as a result, a lot more dangerous than the standard Human Grunt. 

The Apache Helicopter is a dangerous enemy to deal with. Packed with rockets and a 12mm machine gun, they will chew up or blow up anything that gets in their way. Their weak spot is near the engine, rotor, and pilot cockpit. Some areas on the helicopter's body are invulnerable to projectile based weaponry.

The Osprey Helicopter is one of the transport vehicles for Human Grunts. They will re-supply a certain location when Human Grunts on the ground die. They have no offensive capabilities other than the grunts that repel down from them. To destroy them, aim for the rotors or pilot cockpit. Some areas on the helicopter are invulnerable to projectile based weaponry.