Every main survivor design in the original beta of Left 4 Dead was drastically different to what was in the final game, originally using stock photos of models from the 3D.SK website of references to model them after. This is also what the textures of the zombies are based on in the final game.

Once Valve stepped in, they decided to redesign the survivors, because they thought they looked too well-prepared for the apocalypse, which within the game's lore had just begun. They also believed that if the survivors were in a more casual and everyday design, then they would resonate with a wider audience.

Valve also wanted to have cinematic cutscenes in the final game, and thought that the designs were too simplistic and wouldn't translate well into them. So instead of using stock photos for their new designs, they instead hired actors to be directly modeled for the survivors to give them a higher quality design: Bernard Fouquet (Bill), Sonja Kinski (Zoey), Sean Bennett (Louis), & Taylor Knox (Francis).