The Tank

From wikipedia

A huge, muscular Infected capable of throwing large items such as cars or blocks of concrete. The tank keeps a high profile, able to be heard by the survivors from a great distance due to its loud thrashing while running. The immense strength and toughness of the tank makes it a terrible foe in combat. To prevent the tank from camping away from the survivors for too long, a frustration timer is set when the survivors are not in sight. When the timer runs out, the tank becomes uncontrollable and begins stomping and thrashing giving away its position and becoming vulnerable to the survivors. The tank is the toughest of the infected, and is able to withstand an extremely large amount of gunfire before dying.