Roof Runner originated as a mall security guard who patrolled the rooftop during the initial outbreak, only to be infected by a lycanthropic strain mutated from the basement flooding. The combination of contaminated water and full moon exposure triggered a transformation, binding his humanity to the mall's highest point. Now, he stalks the roof as a relentless predator, driven by instinct to prevent any escape from the overrun complex.

Roof Runner possesses enhanced speed and agility, allowing it to traverse the rooftop with unnatural grace, leaping between ventilation shafts and ledges. Its physical form is resilient to conventional weapons, with thick fur providing protection against bites and environmental hazards. The entity exhibits heightened senses, particularly smell and hearing, enabling it to track survivors through noise and scent trails. During full moons, its strength and ferocity peak, making it nearly unstoppable in open areas.

Roof Runner influences events by acting as a guardian of the mall's final escape routes, specifically targeting survivors attempting to reach the helipad or roof access points. It creates chokepoints and forces players to adapt their strategies, adding a layer of supernatural danger to the already dire zombie apocalypse.