When they are encountered in large numbers, are the most commonly-faced member of the Infected hordes and the easiest to defeat. They are completely AI-controlled and are fairly weak. Their strength lies in the fact they attack in groups sometimes as large as several dozen. While they seem capable of ignoring pain, they can still be killed as easily as a normal human can. They are capable of climbing ladders and scaling objects. The default number of Infected that are spawned in a mob is around 30. The infected horde is eerily fast, sensitive to loud noises and movement, and able to attack in ravenous waves. They might not notice you right away, but when they do, watch out—they’re fast, and it won’t take long for them to close the distance. When Common Infected attack from the front, they do approximately 1 damage on easy, 2 on normal, 5 on advanced and 20 on expert. If you are hit in the back, they do 0.5 damage on easy, 1 on normal, 2.5 on advanced, and 10 on expert.
The bodies of former CEDA agents, these Infected are immune to all types of incendiary damage. (Molotovs, Gas cans, stationary fire, incendiary ammo, etc.) These Infected may also drop bile-bombs, whose use is thought to be as weapons against the infected.
Former employees of the Whispering Oaks carnival, these zombies summon other Common Infected by the squeaking of their shoes. Survivors can “honk” the Clown’s nose by using the standard melee on him. They are usually seen leading a pack of common infected. Honk enough noses and you might just get an achievement.
Found in the Passing Campaign, the Fallen Survivor is an Infected that typically flees from Survivors. It is somewhat armored, requiring several hits to take him down. He carries several items that are dropped upon his death, including heath and grenades.
As far as health and damage is concerned, these Infected are the same as a Common Infected. However, the Mud Men have are covered in mud and use this a camouflage. Usually attacking on “all fours,” the Mud Men are faster than Common Infected and can run through water where the Survivors are typically slowed. Also, upon attacking, Mud Men smear mud on the Survivor, obstructing their view. This appears as mud smeared on the television screen.
Personal riot police hired by CEDA, the infection was able to reach them through their armor leaving the Survivors to deal with bullet-proof zombies. It has been hinted that attacking from behind is the only way to kill the Riot Infected with bullets. Fire, explosives and melee attacks are said to still be effective. Riot Infected may drop Tonfa batons upon their death.
Found in the Hard Rain Campaign, the Worker Infected are immune to headshots and are not attracted to pipe bombs. These guys were working on various construction projects around the neighborhood that Hard Rain takes place in. Although they can’t hear the pipe-bombs, they can still hear car alarms so be careful! They also wear shiney reflector vests so that you can easily spot them before it’s too late.
He is an agile Infected who can leap from walls and jump over rooftops. The Hunter always wears a dark hoodie, and what appear to be dark brown sweatpants, and has his outfit taped down, presumably to prevent air from getting trapped in the legs and arms, and slowing him down in mid air. Hunters are primarily identified by a distinctive growl, or the screams they emit when pouncing or when they have sighted a Survivor. This Special Infected has two attacks: a claw attack and a pouncing attack, which pins down a helpless Survivor while the Hunter claws at them. The Hunter will not stop until finished, killed, or knocked off. Also, the actual pounce will cause damage from the impact with a comment coming up telling how much damage was caused by the impact. The maximum pounce damage that can be caused is 25. Flaming hunters, while not as strong as they were upon the game’s initial release, do additional damage and when coupled with pounce damage and team attacks are typically lethal. On rare occasions, 4 hunters can appear at one time in versus modes.
He is an Infected with a long, whip-like tongue that is able to regenerate. The Smoker’s tongue can be launched out of its mouth at high speeds. When the Smoker’s tongue reaches one of the Survivors, it automatically wraps up their body and drags it off toward the Smoker. When constricted, Survivors have a brief moment (1-2 seconds) to shoot the offending Smoker before their arms are ensnared by the tongue; if they fail, the Survivor is helplessly dragged off, and will take damage until either the Smoker or he/she dies. (It isn’t until the Survivor is helpless that they can be “melee’d off.”) The Smoker claws at an ensnared Survivor when they are dragged all the way back to him, while at the same time the Survivor takes damage from the tongue constricting them if an obstacle obstructs them from being dragged to the Smoker. If a Survivor isn’t dragged all the way back to a Smoker due to an obstruction (for example, a Horde surrounding the Survivor) the Survivor will only take damage from the tongue’s squeeze (this damage seems to be the same as when the Smoker is clawing at them, however). When killed, a Smoker leaves a haze of dark green smoke, obscuring the Survivors if they stand in it. Smokers are relatively weak compared to other Special Infected. Only one Smoker is allowed on the Infected team while playing Versus.
He is an extremely bloated Special Infected whose inflation seems to be filled with an odorous slime. They are able to vomit bile; if it hits the Survivors, it covers them, temporarily blinding them and attracting the Horde. When the Boomer dies, it explodes and discharges large amounts of gore and viscera, which will also attract Hordes of Common Infected if an unfortunate Survivor is caught in the blast. In addition, both Infected and Survivors are knocked over by it. For example, this could be used to get a Hunter off of a pinned survivor who is stuck and out of range or accidentally cause a survivor to be pushed off of a ledge. Boomers are relatively delicate. This means it is only able to take a very small number of bullets before it bursts. If Boomers drop from a particularly high place, such as from a roof top into a street, they “pop”, which is an effective means of ambushing Survivors. However, the Boomer does not burst when falling from tall heights in Versus. Like all other Special Infected, it too has a scratch attack, though it isn’t terribly useful unless one is trying to get Survivors to pop him.
This Special Infected plows into Survivors in an effort to grab one. Once it has a Survivor in it’s grasp, the Charger will continue to run until it reaches a barrier and will repeatedly slam the Survivor into the ground. Similar to the Tank in physical structure, it is not as strong nor does it have nearly as much health. The Charger does not take damage from melee (shove) attacks so don’t bother. The quickest way to kill one of these is with a melee weapon. There are plenty of spots in each campaign where you can charge a Survivor off of a ledge and Instant Kill them or Instant Incap them. The Charger has also had a lot of problems. Some say it is ‘Glitchy’ and doesn’t always grab a Survivor when it should. It was originally thought to be a hitbox issue, but the truth is that it’s a Server issue. There is a slight delay between the server and client. So, what you’re seeing is a couple seconds after what’s happening on the server. Because of this, and because of the Charger’s speed, VALVe developers had to add in a slight position correction to account for this lag. This correction doesn’t always work how it should. This means, the slower the server, the worse the charger. If you want a good charger, host locally.
This Special Infected mounts a Survivor and attacks them from behind while literally riding them into various environmental or zombie-related hazards. The Jockey is able to steer Survivors to some degree, but a Survivor can make it difficult. The Jockey has a hunch-back and rather demented appearance. The trajectory of the Jockey’s primary attack can be very hard to get used to. It’s often best to get as close as you can before attempting it. Another way you can ride someone is by simply dropping off of a roof or high position and landing right on top of them. If you do this, you don’t even have to push the attack button. It’s a very common strategy to Jockey someone in to a puddle of Spitter acid. The Jockey can also be used to perform Instant Kills, however, usually when Jockeying a Survivor off of a ledge, they will simply grab on to it and the Jockey will fall to it’s death. This is still a good strategy as it forces one Survivor to hang on the ledge and slows down the entire team.
This Special Infected lives up to its name but spitting mutated acidic phlegm at Survivors, creating an acid pool that does damage to Survivors the longer they stand in it. Much like the Boomer, this character is used to create chaos among Survivors and spread them out. Also like the Boomer, the Spitter leaves her acid pool for nearby Survivors after being killed. The Spitter has very low health and is easy to kill. She’s also easy to spot because she is drooling a trail of acid that glows. It’s best to find a high position away from Survivors. Remember, if acid hits a ceiling, it falls straight down, so you don’t always have to be able to see the Survivors to spit on them. It’s often a good plan to try to spit in areas where Survivors are forced together such as narrow hallways and elevators. The spitter can be a vital tool in Scavenge mode. If a dropped can sits in Spitter acid long enough, it will ignite. However, the Spitter’s acid pool seems to be smaller in areas close to the generator and other important locations.
She is the only one member of the Special Infected initially passive to the Survivors unless provoked. She is also the only non-playable Special Infected, likely considered to be too powerful. She resembles the average female Common Infected, but instead of standing around and idling, she is usually slumped on the ground and making loud noises which resemble sobbing, which can be heard long before it’s ever seen, allowing the player a chance to prepare a plan to deal with it. She has sharpened elongated fingers used as weapons, and has gained a massive increase in strength, enabling her to incapacitate or instantly kill Survivors in one hit. Proximity and flashlights both startle her, though a flashlight will startle the Witch at exactly 4 times the distance mere proximity would. In L4D2, you can find some Witches wondering around. The Suger Mill in Hard Rain is filled with them. Also, in The Passing, you can find a Bride Witch in the wedding area.
He is a muscular Special Infected of gigantic proportions. This monster is capable of throwing large items such as cars or blocks of concrete it rips out of the ground, and bashing through otherwise impenetrable walls. The Tank keeps a high profile, able to be heard by the Survivors from a great distance due to its loud growls and the thrashing it makes when running. The immense strength and sheer toughness of the Tank make it a terrible foe in combat, especially to inexperienced or uncoordinated Survivors. Occasionally, players are able to take on the role of the Tank in Versus Mode. When Survivors gain control of it, the Tank has a frustration meter that slowly drains when he doesn’t hit the Survivors, the frustration meter also depletes as long as the Tank can not see the Survivors. Once the frustration meter is depleted, control of the Tank is given to another player if available. If the second player’s frustration meter is depleted, the Tank becomes AI controlled. Also, when players are controlling the Tank, they can break down walls highlighted by yellow cracks. Though multitudes of Common Infected can break down the walls, as can other Special Infected, only Tanks can break through steel. Should the Tank be caught on fire, it has roughly 30 seconds before it dies unless the fire is extinguished. In Campaign mode, when the Tank is set on fire, it runs 30% faster than when not on fire. However, on versus mode, when it’s set on fire while controlled by a player, it runs about the same. The AI Tank still runs faster when set on fire. AI Tanks will always attack a person that is on a Minigun first as well as a person who has melee’d him.