Crowbar

The Crowbar is a new close-combat weapon introduced in Left 4 Dead 2.

The crowbar is not really meant to be used against Special Infected, because using it on a Boomer would cover you in bile, and killing a Spitter would leave you right in the middle of the goo. It would also take time to get to a Charger, Jockey, Hunter or Smoker. Against a Tank or Witch it would do little to no damage.

Trivia

 * The crowbar is likely a reference to another of Valve's popular game series, Half-Life, where the player character's first weapon is a crowbar.
 * The way that the player holds it is very similar to the way you hold it in Half-Life.