Fast Zombie

The Fast Zombie is the resulting manifestation of a human host under the control of a Fast Headcrab. As the name states, Fast Zombies are extremely agile; being able to climb, run and jump.

Overview
Fast Zombies are much leaner than other Zombie variants, stripped of their outer skin, some body tissue, and most or all organs (revealing large parts of its skeleton). Fast Zombies also have longer claws than other zombies. Whether they are merely a product of continued mutation, or some toxin produced within the headcrab, the reason for these differences is unknown.

What distinguishes the Fast Zombie from other zombies is its ability to climb and move quickly, thus being able to confuse and surprise its prey. Fast Zombies also make loud wails while attacking and can be heard babbling while idle. Fast Zombies stand on two legs while slashing with its claws or standing up, but move on their legs and arms while running or climbing.

Like Standard Zombies, Fast Zombie torsos can survive when separated from the legs. The only difference is that Fast Zombie torsos crawl and attack faster.

In Episode Two, in the chapter Riding Shotgun, a Fast Zombie at one point succeeds in latching onto the hood of the player's Muscle Car while the car is moving. (Alyx kicks it off shortly after its initial latch-on).

Fast Zombies, if needed, will lunge at its target to close any distance quickly, and will slash the target upon coming into contact. This attack does the same amount of damage as the normal slash attack.

Tactics
Fast Zombies, although they can be very frightening, aren't particularly dangerous on their own because their attacks are fairly weak. Unfortunately, they - more often than not - travel in "packs" of three to four. They're also not particularly hardy - they're just difficult to hit due to their fast and generally unpredictable movement. If facing a Fast Zombie, use the shotgun and aim for the head (some find the SMG works well for packs).

On the rooftops of Ravenholm in Half-Life 2, the biggest threat is actually falling off by surprise when a Fast Zombie suddenly attacks, thus causing fall damage while the zombie pursues.

During "We Don't Go to Ravenholm..." and the rooftop battles with the fast zombies, they constantly climb up building's gutters. While doing so, the player will hear a rattling beat, and the gutter will move side-to-side. However, the enemy below might not be a fast zombie, due to the fact that if any kind of zombie/headcrab touches the pipe, it makes the same noise. After Grigori throws Gordon the shotgun, grab it and look for the gutters that are rattling at the edges of the rooftop. Aim over the side of the building and shoot the zombie before it reaches the top. Doing this will save some time before more fast zombies become overwhelming. The magnum also works well if or when shotgun shells have ran out, although there are plenty of ammo caches for the shotgun throughout the town.

When a fast zombie is approaching, try to use the environment as an advantage. Quickly hide behind cover and stay close to the edge and wait for the zombie to come around the corner. Fire the shotgun at it as soon as it is in range. Shoot the zombie as it leaps, instantly killing it in mid air. It is recommended to use the magnum for this, however, because the shotgun has a slightly lower precision. Hiding behind cover will prevent the fast zombie from using its leap attack that most players fall victim to due to the surprise and disorientation it causes. This tactic will work with most other enemies, except for, of course, the ones that throw or, in the Zombine's case, hold grenades.

Fast Zombies can be detected by the distinct howling they tend to emit, though at closer ranges they can be found by still other noises; growls, babbling, and screams.

In Episode Two, Fast Zombies sometimes pretend to be dead, then jump up to attack when approached. This tactic was also used by Standard Zombies in Half-Life 2. When investigating an area littered with zombie corpses, check if any still have headcrabs attached to their head, as this is a good sign the zombie is merely playing dead. If so, shoot them in the head just in case. It pays to be sure. One is also seen digging in a dumpster, showing that fast zombies may be curious or of a higher intelligence than their brethren. Supporting this argument, if a grenade is thrown into the dumpster while the fast zombie is still inside, the grenade may be thrown back out. Fast Zombies also tend to hide behind large objects. There is no real way to counter this. Simply stay alert, and be ready to fire when the zombie reveals itself. They also like to lurk in dark areas, so be alert.

Behind the scenes

 * The Fast Zombie was made from the Alien Assassin.
 * It originally had trousers and socks, while its skin was greenish.

Trivia

 * During the Riding Shotgun chapter in Episode Two, shortly after a Fast Zombie clings to the car, the Headcrab covering its face slightly lifts up, revealing the skull underneath.
 * Despite the mutilation of the body and absence of most muscle tissue, a Fast Zombie is still able to jump great distances and move very quickly.
 * The scream emitted by the Fast Zombie while executing its leaping attack appears to be a sped-up version of an infamous stock sound effect, the Howie Scream, which has been used in many movies and TV shows. The Poison Headcrab second scream, , appears to be a sped-up version of  . The Half-Life series uses many stock sounds heard in many other video games and films.
 * Removing a Fast Zombie's headcrab reveals that the host has an uncovered skull with no skin.
 * Starting in Half-Life 2: Episode One, Fast Zombies torsos can be cheat spawned using the code "npc_fastzombie_torso". Spawning a torso near Alyx Vance will cause it to climb up her legs and to her face.
 * In Episode One, Fast Zombie torsos crawl while holding their bodies slightly upright. In Episode Two, the torsos hold their body a little lower, which allows them to crawl faster.
 * After a Fast Zombie hits you, it stands still, doing a gesture, then lets out a hissing cry as if it were angry.
 * The Fast Zombie shares many traits, and may have been the inspiration for, the Hunter from Left 4 Dead, another of Valve's games.

List of appearances

 * Half-Life 2
 * Half-Life 2: Raising the Bar
 * Half-Life 2: Episode One
 * Source Particle Benchmark
 * Half-Life 2: Episode Two