Bill

William "Bill" Overbeck is one of the four playable Survivors in Left 4 Dead, a Vietnam veteran who served in the US Army 1st Special Forces Group. His combat skills have helped to keep him alive, he is also the oldest of the group. In official media, he is usually seen wielding the assault rifle, probably to complement his backstory. He is voiced by Jim French.

Official description
It took two eventful tours in Vietnam, a handful of medals, a knee full of shrapnel, and an honorable discharge before the unthinkable happened: Bill ran out of wars. But now an army of undead has declared war on humanity. After decades of aimless drifting and dead-end jobs, Bill's finally gotten back the only thing he ever wanted: an enemy to fight.

Unsaid Bonuses
Although no programming lines or guides outright state this, it has been observed that, playing as Bill, it will take slightly fewer assault rifle rounds to take down boss enemies. The reload animation also seems to be slightly shorter.

Trivia
On the poster for Dead Air, his beret has a blue, star bordered U.S. Army General Service Beret flash on it, not the Yellow U.S. army 1st Special Forces Group beret flash as appears in the game, and on the rest of the posters.

Quotes

 * "Francis, was that you or the sewer?"
 * "I ain't walkin' to the roof!"
 * [ Hospital elevator, responding to Zoey questioning if things will return to normal ]"I'll see peace back on Earth if I gotta murder every one of these bastards with my bare goddamn hands!"
 * "You call this a 'zombie apocalypse'? This is nothing compared to the Great Zombie Attack of '57!" "...Nah, I'm just horse shittin' ya!"


 * [ When reviving a survivor ]"Hey no shame kid, I would have pissed my pants too, but we need to get out of here"
 * [ When healed or revived ] "That was unnecessary... but, thanks."
 * "Check your fire!"
 * "Secure that weapon!"
 * [ Picking up a pipe bomb ] "I'd rather have a grenade, but this'll do."
 * "An assault rifle; This shit's gettin' more like 'Nam every second."
 * "Reeloooaaaadiiiing!"
 * [ When slimed by a Boomer ] "God damn it, son of a bitch!"