TWD

The Walking Dead takes place after the onset of a worldwide zombie apocalypse. The zombies, referred to as "walkers", shamble towards living humans and other creatures to eat them; they are attracted to noise, such as gunshots, and to different scents, e.g. humans. Although it initially seems that only humans that are bitten or scratched by walkers can turn into other walkers, it is revealed early in the series that all living humans carry the pathogen responsible for the mutation; therefore, anyone who dies will reanimate as a walker. The mutation is activated after the death of the pathogen's host, and the only way to permanently kill a walker is to damage its brain or destroy the body entirely, such as by cremating it.