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The Poison Zombie is the resulting zombie of a human host under the control of a Poison Headcrab. The mutations that take place produce a bloated, slow-moving zombie that is capable of carrying additional poison headcrabs.


Poison Zombie at Bridge Point.

Poison Zombies are bloated, reddish purple, slow-moving zombies. They are almost always seen carrying three additional Poison Headcrabs on their back. It appears that the Poison Zombie's model is an old man's, but its stooped posture and shuffling gait could also be caused by the weight of the attached headcrabs, or (as seen by the exposed spinal column) because it's missing all the supportive muscles from its back which would allow it to pull the upper torso into an upright standing position.

The Poison Headcrabs riding on the Zombie's back can leap off when needed in order to attack on their own, but cannot, or will not reattach themselves to the Poison Zombie once left.

Another trait that distinguishes the Poison Zombie from other zombie types is its endurance. Poison Zombies can take three times as much damage as other zombies before collapsing.

Poison Zombies themselves are not poisonous but rather rely on the hitch-hiking poison headcrabs to attack first. Then, it resorts to its claws. Poison Zombies can be detected by their loud, strangulated breathing and muffled groans. They also emit loud, whale-like howls when taking damage.

Poison Zombies are unique in the fact that the Headcrabs attached to their bodies appear to be interacting with their host. While other Headcrab zombies serve as a host for individual Headcrabs, the Poison Headcrabs attached to a poison zombie appear to be from it. The fact the poison zombie is off-color and bloated would suggest that the Headcrabs are either sucking nutrients from the body (which would explain why the Headcrabs on a poison zombie's body seem to pulse), are causing enough damage to make the host lose almost all of his blood, or are using the body to store or create their acute neurotoxin. It has also been speculated that Poison Headcrabs may lay their eggs in their hosts' bodies, which would explain the hosts' bloated appearance and the multiple poison headcrabs which cover them. It is also worthy to note that if the player kills the Poison Zombie before it can "release" the Poison Headcrabs from its back, the headcrabs will also die.

It should be noted that unlike other types of zombies, poison zombies cannot be cut in half.

Poison Zombies are first encountered in Half-Life 2 Chapter 6: "We Don't Go To Ravenholm..." after the player gets the Shotgun and takes the elevator. In Episode One, they are first encountered in the Hospital, in the Chapter Urban Flight. In Episode Two, they are first encountered in an abandoned Resistance outpost, where a combine thumper can be found, in the Chapter This Vortal Coil.

In the game files there is a prototype model of the zombie with the headcrab untextured, is similar to the Fast Zombie.

In the beta files exist textures of an unused model of the poison zombie:


Poison Zombies can take a lot more damage than other zombies (roughly 300%), and have better attack capabilities.

  • The most effective weapon against poison zombies is fire; when hit, the Zombie will set alight the Headcrabs as well. A very good tactic is to grab a propane tank or gas canister with the Gravity Gun, pop out of cover, light up the Zombie, and then take cover or leave the area before it throws more headcrabs. It will die and take its passengers with it without causing any damage. If possible, avoid the Zombie after igniting it as it can take a while to kill the Zombie. If no flammable objects are present, take advantage of the Headcrabs and their host's flammable nature by chucking hand grenades or firing MP7 grenades. If grenades are not available, try to find explosive barrels. However, while the explosion of a grenade and/or an explosive barrel cannot light the Poison Zombie up, it can inflict decent damage on it.
  • A effective technique is to take Dog's ball into Ravenholm with you as it will draw the Zombie's fire and allow an easier kill with less risk of taking damage. The player could use the crowbar in this case, as the zombie's AI prioritizes Dog's ball over the player.
  • At close range, move around while attacking to avoid being hit by the thrown headcrabs. Normally, there are three riding headcrabs. When a thrown poison headcrab comes into contact, health points will drop to 1, but will gradually increase by increments of 10 as the HEV Suit administers an antidote to the venom. Therefore, it is advised not to use the Crowbar against incoming thrown headcrabs, especially when being engaged by other enemies like the Combine Soldier, zombies, fast zombies or the Zombine. The Gravity Gun can sometimes push back the incoming Poison Headcrab, but this is not always safe. If sufficient room is available, wait for the Zombie to throw all headcrabs off its back. The Zombie should be a minimal threat without the hitch-hiking poison headcrabs on its back, thus allowing the player to finish off the Zombie with lighter weaponry or the Crowbar.
  • When the player has an energy core to spare, it is recommended to equip the Pulse Rifle and use its alternative fire on the Zombie, which will cause the Zombie to disintegrate. All headcrabs will detach but instantly touch the fusion orb as well which means immediate death.
  • When using the Crossbow against it, get away from the poison zombie and aim at the Headcrabs on its back. This way, the Poison Zombie should die without releasing its poison headcrabs.


  • There is no difference between the Poison Zombie and the Half-Life 2 Beta "Fast Zombie", aside from the spine on its back and the skin. This is easily notable by the feet. [source?]
  • The Poison Zombie appears to be several times stronger than its brethren: On multiple occasions, poison zombies can destroy entire doors. In Half-Life 2: Episode One, in the hospital level, several Standard Zombies are seen trying to claw open a doorway, but it is not until the Poison Zombie arrives when, with tremendous and seemingly explosive force, the door is destroyed. They can also toss props faster and farther than regular Zombies.
    • Despite this, the Poison Zombie inflicts slightly less melee damage than regular zombies due to only having one attack animation.
  • Some of their sounds seem to be reversed donkey and bovine sounds.
  • When a poison zombie makes it into the path of a barnacle, the game will crash. This can be seen without the use of cheats/mods towards the end of Anticitizen One in the tunnels after Alyx is captured. The player should lure the Poison Zombie towards the nearest barnacle using the chain-link fence as a ramp. No attempts have been made to fix this.
  • The Poison Zombie's second breathing sound (pz_breathe_loop2.wav), sounds like a deeper variant of Left 4 Dead 2's Jockey.
  • If the player uses the cheat "notarget," it can be seen that the Headcrab on the head of the Zombie is bouncing.
  • One of the death sounds for the poison zombie is someone making an obnoxious sound, and a laugh is heard in the background. This is most likely a goof in the sound design, as when they were making sounds someone left the laughing part in.
  • If the player is of low enough health, Thrown Poison Headcrabs can act as a last ditch effort to obtain health as the amount HEV recovers is always the same, but is ill advised while the Zombie is still present.
  • The alert sounds for the poison zombie are actually just the sound of the fast zombie's post-attack sound, slowed down and separated into separate sound files.




List of appearances