They are the main antagonists in the novel & film, as well as the primary enemies in the video game of the same name.
In the novel, the Zombies started in China, with "Patient Zero", a young boy, who was fishing with his father but his canoe capsized, and he was bitten by a submerged Zombie. From him, the outbreak spread global, from black market organ donations, infectious blood, and zombie attacks. The patients could not be treated because all cures failed; and in 16 to 20 hours they reanimate as the Undead. A powerful virus, Solanum, infects nearly all of humanity, turning most of them into carnivorous predators(that's more than capable of destroying life on earth), which can have superhuman endurance as they never tire. This, coupled with their inability to feel pain, as well their quasi-immortality from their Oxygen Independence is their greatest weapon.
Humanity eventually wins the war, but at great cost, in a decade of fighting against the Undead hordes which engulf entire cities.
The origins of the outbreak is unknown. Those bitten are transformed into zombies after 12 seconds. They are known to being attracted to noises such as music. They can sense if a human victim is healthy. They can also climb on to each other like ants climbing over the wall. The infected do not bite people who are seriously injured or already terminally ill, since they would be unsuitable as hosts for viral reproduction.
Differences between Book and Movie Versions
- In the book, the virus is called Solanum, whereas in the film, the virus is rabies, or the Spanish flu from early 1900s.
- In the book, the zombies are a tribute to Romero's slow mindless zombies which are so mindless they will plunge off cliffs in pursuit of their prey. In the film, however, the zombies have a greater intelligence, almost sadistic, and enjoy chasing their prey down and can work out routes to do so (for instance when the zombies scale the Jerusalem Wall).
- In the book, the zombies can only be killed when shot in the head. In the film its the same, but due to the speed of the zombies it looks as if they can be shot anywhere. Also the zombies are attracted to noises in the film, in the book its never stated if this is so.
- The zombies in the film turn almost instantly, in five seconds. In the first case there is actually a voiceover counting down the transformation sequence. However in the book the zombie transformation takes sixteen hours at most and it actually varies from person to person.