The Infected

The Infected are the "zombies" in Left 4 Dead. They are more akin to the zombies from 28 Days Later than to the more popular slow, shambling type. Instead of being dead, they are living humans who have been infected with a mutated virus. There are six varieties, four of which are playable. Five varieties are considered "Boss Infected" which have special abilities in addition to doing more damage against the Survivors. All AI-controlled Infected are randomly spawned by the Director.

Normal Infected

 * Also see: The Horde

Normal Infected are the most common enemy faced and they are the easiest to defeat. They are completely AI-controlled and fairly weak. Their strength lies in the fact they attack in groups sometimes as large as several dozen, known as the Horde. 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 Witch


The Witch appears only once per map, and is passive unless provoked by flashlights, gunfire, or Survivors getting too close. She is very powerful and is capable of killing players with a single attack as well as sustaining much damage before dying. While the Witch can be killed, it is best to avoid startling her unless absolutely necessary.

The Screamer
The Screamer is a possibly cut unplayable Infected character that would have probably only appeared once per map and screamed alerting all nearby Infected when any of the Survivors were seen, sort of like how the Boomer's vomit makes all the Horde Infected attack the Survivors. A sound file and a picture of the Screamer can be found in the Left 4 Dead .vpk files once unpacked, by searching for screamer.vtf, and com-thescreamer.wav.

The Boomer


The Boomer is a morbidly obese Infected that spits vomit at survivors, which blinds them and draws other infected to them. At a distance, the Boomer is little threat, since he is extremely slow. However, he can vomit on Survivors, attracting the Horde. When he dies, he explodes and covers any Survivors who are close enough in bile. If a Boomer is killed close to the group of players, the entire group could be doomed.

The Hunter


The Hunter is extremely similar to the fast zombies from Half-Life 2, although far less charred. The Hunter is extremely quick and agile, and is capable of scaling walls. Additionally, he can pounce players and pin them down until killed or shoved off by another Survivor. If the Hunter remains motionless against a wall, he will turn invisible. Since this "class" is extremely agile, he is also physically weak and cannot take much gunfire.

The Smoker


The Smoker is an ambush class who can strangle Survivors with his long tongue. The help of another survivor is required to escape from a Smoker's hold. As his name implies, Smokers can emit smoke to impair Survivors' vision and voice communication when in danger, or automatically when killed. The Smoker can drag players that he has captured with his tongue.

The Tank


The Tank is the strongest of Boss Infected. Though slow, he has incredible strength and resistance. To counter this overwhelming advantage, the Tank has a frustration meter that goes up whenever the Survivors aren't in view. When the meter is full, the player loses control of the Tank. The Tank is capable of throwing large objects with sufficient force to injure Survivors.