The Infected

"I'll see peace back on earth if I've gotta murder every one of these bastards with my bare god damn hands!"

- Bill

"It's them or us!"

- Coach

The Infected are Left 4 Dead's take on the classic zombie. Rather than being undead, they are living humans who have been infected by the Green Flu virus, causing massively increased aggression and loss of many higher brain functions, such as speech and self-preservation. Also unlike zombies, the Infected seem to have no interest in eating their victims. Through some unknown mechanism, a small percentage of infected humans will undergo a dramatic mutation, eventually turning into one of the special infected. There are nine varieties of the Infected, 7 of which are playable. Eight varieties are considered "Boss Infected", or "Special Infected", which have special abilities in addition to doing more damage against the Survivors. All AI-controlled Infected are procedurally spawned by the Director.

Common Infected


Common Infected, as their name implies, are the most commonly-faced enemy, as well as the easiest to defeat. They are more akin to the antagonists from 28 Days Later than to the typical shambling zombie. They are exclusively AI-controlled and fairly weak. Their strength lies in their tendency to attack in large groups of up to several dozen, known as hordes. While they seem capable of ignoring pain, they can still be killed easily. They are capable of climbing ladders and scaling objects, as well as breaking down weak walls and doors. This type of Infected are attracted by flashlights, loud noises such as car alarms, or by Boomer bile. They appear to lack self-preservation, but do appear to have some intelligence as in the Hard Rain campaign the Horde will attack when the storm picks up and there is minimal visibility (or maybe they get really aggressive or get attracted to the lightings and noise of the storm)

Hordes
"Here they come!"

- Bill

A horde is a large group of Common Infected that will rush the Survivors at random intervals, after triggering a car alarm or other Panic Events, Crescendo Event, during a finale, or when throwing a Bile Bomb.

Uncommon Infected
Left 4 Dead 2 introduced five special types (seven counting Jimmy Gibbs and the cut Fallen) of Common Infected known as "Uncommon Infected" or "Uncommon common". The DLC coming Spring 2010, named The Passing will introduce an eighth type, but no further details are known. Each Uncommon Infected is unique to the campaign it appears in. Dead Center features the Infected CEDA Workers, Dark Carnival features the Clown Infected, Swamp Fever features the Mud Men, Hard Rain features the Worker Infected, and The Parish features the Riot Infected. Each has its own special ability that makes them slightly more dangerous than Common Infected.

The Witch
The Witch generally only appears a few times per campaign, and is passive unless provoked by flashlights, gunfire, or Survivors in close proximity. She is very powerful, and is capable of incapacitating/killing players with a single attack, as well as sustaining much damage before dying. Luckily, many hints are given to let Survivors know when a Witch is nearby. The Witch cries loudly, which Survivors will mention they hear, warn you to turn off your flashlight, and dramatic music will play. While the Witch can be killed, it is best to avoid startling her unless absolutely necessary. The most common means of her being startled is by staying near her too long or bumping into her. However, advertised in the intro movie of Left 4 Dead it shows the witch being startled by a survivor shining a flashlight on her. Some believe that the witch is agitated by the light, but some others think that the light is not what scares her, but rather it is just that if you get close enough to shine the light, you being so close is what startles her. This is subject to some controversy. The Witch is very rarely found in small rooms and normally stays off the main route but has been found in front of safe rooms, doorways and in the middle of streets. Once a Witch has killed a Survivor she will retreat out the area and completely disappear. However, in some strange cases, the witch has been known to kill the closest survivor to it. This does not usually happen, and when it does, the witch runs off as normal after killing the survivor. Also, if a player blocks the Witch from attacking the Survivor who startled her, she will attack the Survivor blocking her and either incapacitate the blocking player and run away or incapacitate both the blocking player and the player who startled her. If a Witch must be killed then you have one of four options:
 * 1) Sneak up on the Witch and attempt to kill it with the Auto Shotgun. (If the initial head shot connects but does not kill, only one or two more shots should kill it.)
 * 2) Have one player move far back, as far away from the Witch as possible. The Witch will target the player that disturbed it, meaning it will attack the farther away player providing he or she shot or shined a flash light on it. This will allow the other players to shoot the Witch as it is running to the farther away player. When using this method watch for Special Infected as they may ruin the plan or even kill the team if they attack at the right moment.
 * 3) In Left 4 Dead 2, two or more players can quickly kill the witch with a coordinated attack using melee weapons, or a single player with a chainsaw. The amount of players necessary to kill her without a chainsaw will vary based on difficulty, two is typically enough.
 * 4) In Left 4 Dead 2, if a player has the explosive ammo upgrade on any primary weapon, they can use it to stun the Witch, leaving her vulnerable for attack, making her much easier to kill.
 * In Left 4 Dead 2's Hard Rain campaign, a large number of Witches have infested an abandoned sugar mill, which the Survivors must traverse to obtain fuel for their rescue boat. An achievement, Sob Story, is earned for navigating the sugar mill without killing any of them.
 * The Witch's music cue.



The Wandering Witch
The Wandering Witch appears in Left 4 Dead 2. She is seen only in the daylight hours, aimlessly wandering around and sobbing loudly with her head in her hands. Her constant movement makes her harder to avoid, but she is also far more introverted and reacts only to direct attack or physical contact. One can even damage her slightly with out startling her.

The Wandering Witch remains as vulnerable as ever to headshots from a shotgun, and her more placid nature makes her much easier to cr0wn.

Playable Infected
Playable Infected, or Special Infected, have been heavily mutated by the Infection, giving them "enhanced abilities". Each has a unique ability that a Survivor cannot face alone, making them the true teamwork testers in this game. They do not appear to be attracted by car alarms or loud noise and seem to have a higher degree of intelligence than Common Infected. They are deadly to lone wolf Survivors, but can be easily avoided and defeated through communication and synergy.

The Boomer
The Boomer is an Infected that vomits a special bile at Survivors, which temporarily blinds them and draws Common Infected to them. At a distance the Boomer is little threat, his large size, slow speed and low health make him an easy target against any weapon at mid or long range. However, if within range he can vomit on Survivors, attracting the Horde. When he dies, he explodes, covering any Survivors who are close enough with bile, blinding them and causing them to stumble backwards. The Boomer is notorious on the Expert difficulty for being able to snipe survivors. Boomers can be anticipated because of the near-constant gurgling they make. In Left 4 Dead 2 there is also a female Boomer, although it has no effect on gameplay.

The Hunter
The Hunter is similar to the fast zombies from Half-Life 2, although they are not as mutated on the outside. The Hunter is extremely quick and agile, capable of quickly scaling walls. Additionally, he can pounce and pin down Survivors, clawing at their abdomen until either the victim is dead, or the Hunter has been knocked off by another Survivor. They are not the most physically robust Infected, having relatively low health, and thus it doesn't take very much to kill them. When the Hunter crouches down in preparation to pounce, it growls, giving it away to any nearby Survivors. However, whilst standing it makes no noise. The Hunter is the only Special Infected that can remain absolutely silent. In Left 4 Dead 2 they can be killed with a melee weapon while in the state of pouncing by aiming upwards and hitting although this is fairly difficult as timing is vital and it's easier to kill them from a distance with a high powered primary weapon.

The Smoker
The Smoker is an ambush class who can strangle Survivors with his long tongue, similar to Half-Life ' s Barnacle. The help of another Survivor is required to escape from a Smoker's hold. As the name implies, Smokers emit smoke to impair Survivors' vision and voice communication when killed. A Smoker also will frequently cough, letting the Survivors know when he is in the area. The Smoker can drag players that he has captured with his tongue towards himself, though he remains stationary and cannot move. The Smoker is also momentarily paralyzed for a few seconds after having his tongue removed from his captive by another Survivor.

The Tank
The Tank is the strongest of the Special Infected and is reasonably fast, only slowing if hit with automatic weapons fire or walking through flame. If any Survivors at 40% or above health (including health gained from pain pills or the Adrenaline injector) are running away from the Tank, it will not be able to catch them as they can run slightly faster. The Tank has incredible strength and resistance, his punch can send Survivors flying, rendering them temporarily defenseless. The blow can also send Survivors off high hazards to their deaths. He is also capable of throwing chunks of concrete that he rips out of the ground to momentarily stun Survivors, and can punch large objects (logs, dumpsters, cars, etc.) in the direction of survivors with enough force to incapacitate them instantly. In expert mode, a single hit from the tank will incapacitate Survivors. Nevertheless the Tank will die within 30 seconds if set on fire, except in Versus. When controlled by a player, the Tank has a "Control Meter" that slowly runs out if the Tank has not hit the Survivors for a period of time. Unless the player is able to locate the Survivors and hit one of them, the control of the tank will slowly lessen, and once it runs out, the player will lose control of the Tank to another randomly assigned player. When idle the Tank makes loud wheezing and rasping noises reminiscent of a rabid animal. The Survivors are alerted of an approaching Tank by dramatic music, furious roars and, when he is dangerously close, the screen will start to shake. The Tank is a Special Infected although in Left 4 Dead 2 it does not appear on the screen text when killed. On the left of the screen when killed, a Special Infected message appears such as "Coach killed Hunter", when a Tank is killed, no such message is displayed. The Tank's music cue.

The Charger
The Charger is a Special Infected appearing in Left 4 Dead 2. The Charger grabs the first Survivor and carries, continuing to run forward and knock down other Survivors in its way. Once the Charger has hit a wall or other surface, or after it has run a certain distance, it will begin slamming its captive into the ground until an ally frees them. It appears to have a rocky or calloused surface on its larger right arm, which may be what it uses to inflict most of its force when charging; while its other arm appears to have no bones or muscle, flopping around like a rag doll. Because of its hulking size, the Charger cannot be shoved off with melee, and must be killed in order to release its victim. Any Survivor that has been knocked out of the way during its charge will fly a considerable distance, and slowly stand back up; making the Charger a deadly foe in cramped hallways or near high passageways.

The Jockey
The Jockey is a Special Infected that appears in Left 4 Dead 2. It is a smaller, hunched back Infected that attacks Survivors by clinging to them from behind and literally riding the Survivor while attacking them. He can also shift his weight around and cause the Survivor to stumble in his desired direction giving this Special Infected a type of control over the Survivor. Survivors who are being ridden by the Jockey can attempt to 'resist' the Jockey, which will allow other players a chance to catch up and knock the Jockey off. Jockeys can ride Survivors into dangerous situations, such as into natural hazards, Witches, or other infected. The Jockey seems to have a spinal disease, similar to Kyphosis, giving him a hunched appearance. He also has a maniacal laugh, is constantly twitching, giving him sort of a hyper-active nature. Like the Hunter, the Jockey can be killed before riding the player by aiming upwards with a melée weapon such as an Axe and hitting the Jockey as it leaps. It is interesting to note that the Jockeys mind was trapped in a state of Mania during the initial outbreak and thus, is the reason for his sadistic nature and maniacle laughter.

The Spitter
The Spitter is a new Special Infected in Left 4 Dead 2. She spits an acidic phlegm bomb that spreads upon impact; any Survivor caught within the acid puddle will take increasing amounts of damage, forcing them to move or become incapacitated. The spitter has a mutated right foot as seen in the picture to the right. The Spitter's primary role is to separate the Survivors when they hide in enclosed spaces or group up. When Spitter is killed an acid puddle spreads under and around her corpse, causing the same type of damage as her phlegm bomb. The Spitter plays a particularly important role in Scavenge mode, as her phlegm can be used to ignite gas cans.

Behind the Scenes

 * The idea of fighting mass hordes of melee-only Infected originated from a quick mini-game Turtle Rock Studios made while programming their Counter-Strike Source bots. The bots had knives, while the players had SMGs to fight them off with.
 * Originally, there was going to be a Special Infected named The Screamer. He would run from Survivors, hide, then let out a scream attracting the horde; he was removed as game testers found it too difficult to locate and kill him before he could summon a horde, and his Horde-summoning ability was given to the Boomer's bile. Although in Left 4 Dead 2, there exists a Clown Infected, a type of Uncommon Infected, which can summon a small horde of infected around him with his squeaky shoes.
 * In the Left 4 Dead sound files there are sounds for an infected dog, it seems to have been cut, but all of the sounds are still in the game files. Some sounds have been recycled for the Hunter.