Louis

Louis is one of the four playable Survivors in Left 4 Dead. For the original concept of him, he was an assistant manager at a local retail electronics chain store. Now he is a Junior Systems Analyst in his company's IT department. His clothing resembles the typical business man, but bears a resemblance to Shaun from Shaun of the Dead, who wore a red tie and white shirt. In official media, he is usually seen wielding a submachine gun or dual pistols. He is voiced by Earl Alexander.

Official description
Louis had been working up the courage to quit his job as Junior Systems Analyst at his company's IT department when a virus showed up and downsized the world. Now Louis has a new set of goals (live long enough to succeed) and a new set of tools (guns, sharp objects, etc.) to help him achieve them. With any luck, he'll figure out how the new management operates before they get a chance to murder him.

Unsaid Bonuses
Although no programming lines or guides directly confirm this, it has been observed that, playing as Louis, it takes slightly more assault rifle rounds to down targets yet the reload time seems moderately decreased for him. He also appears to make a slightly wider spread with a Molotov.