Now we have tank the most bad ass and dangerous of them all!
The Tank is the biggest and strongest of all the Infected, and can easily wipe out a team in seconds. He is the only player-controllable "Boss Infected". He is reasonably fast, only slowing if hit with large amounts of automatic weapons fire or when lit on fire (Versus in Left 4 Dead only and any mode aside Versus on Left 4 Dead 2). If any Survivors at 40% or above health (including health gained from pain pills or the Adrenaline Shot) are running away from the Tank, he will not be able to catch them, as they can run slightly faster (unless the Tank in question is an AI Tank in Left 4 Dead).
The Tank has incredible strength and resistance; his punch can send Survivors flying, rendering them temporarily defenseless and stunned. On Expert difficulty, this will instantly incapacitate a Survivor. The blow can 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, dealing the same amount of damage as a punch would. He can also punch large objects such as cars, dumpsters, forklifts, etc. in the direction of Survivors with enough force to incapacitate them instantly.
Nevertheless, the Tank will die within 30 to 45 seconds if set on fire (varying with the difficulty), and will move faster when alight. In Versus when it is controlled by a player, the Tank has a "Control Meter"; unless the player is able to locate and hit one of the Survivors, the Control Meter of the Tank will slowly lessen, also hitting large objects at Survivors does not bring the meter up. Once it runs out, the player will lose control of the Tank to another randomly assigned player. When idle, the sound that a Tank makes is heavy breathing, along with low grunts and sometimes roars. The Survivors are alerted of an approaching Tank by dramatic music, furious roars and, when they are dangerously close, the screen will start to shake. The Tank's Music Cue
The tank has 3 designs actually! But the last one I'm gonna show I have no idea from which game?
The very tan and brown pants is tank's second design in the second game