Zombies

Zombies, mostly referred to in-universe as walkers, are an antagonistic force that serve as the primary catalyst for the events within The Walking Dead universe. They serve as universal antagonists.

Etymology
The English word "zombie" is first recorded in 1819, in a history of Brazil by the poet Robert Southey, in the form of "zombi." The Oxford English Dictionary gives the origin of the word as West African, and compares it to the Kongo words "nzambi" (god) and "zumbi" (fetish).

Definition
Zombie: The reanimated corpse of a human being that has regained limited function and mobility, as well as developed an insatiable hunger for flesh.

Overview
Reanimated human beings, while not immortal, will not "die" under typical conditions that would ordinarily cause the death of a living person. They do not appear to feel or respond to pain, can survive even the most brutal injuries, and despite their bottomless appetite for flesh, they do not need food, water, or sleep to function.

They show no other bodily function that relates to a human, showing no signs of self-healing or response to extreme temperatures. The brain maintains limited abilities of the body, allowing for movement of the limbs (provided that they are not decomposed to the point where the bones are not strong enough to bend without breaking), jaws, neck, and even the use of its sensory systems. While the walkers are notoriously weaker than humans, the only way to kill one is to destroy the brain. Despite severely weakened frames, they will continue to hunt for living animals to consume. Even when decapitated, the head will remain active, even though it would be practically harmless at such point.

Nicknames
The term "zombie" does exist within The Walking Dead universe.

Walkers
"Walker" is a term for a member of the legions of the mobile deceased, who have come to dominate the world following the outbreak of the contagion that spawned them. This is the term used most frequently by Rick Grimes' and Lee Everett's respective groups of survivors, and to refer to reanimated corpses who are not dormant.

The Zombies of "The Walking Dead"
Zombies within The Walking Dead universe are Robert Kirkman's version of George Romero's Night of the Living Dead zombies.

Zombies are relatively weak and unintelligent as individuals, but are dangerous in large numbers and in tight spaces. They are the main antagonists within the post-apocalyptic world of The Walking Dead. The vast majority of the human population (6.3 billion people as of 2013) has been wiped out by zombies, which at their peak, outnumbered humans 5,000 to 1. This leaves about 1,400,000 survivors left.

As a species, Kirkman's zombies do not evolve and are permanently doomed to just deteriorate until there's nothing left but the skeleton.

Transmission

 * Fluid Contact/Bites/Scratches: Though physical contact with a zombie's saliva or blood will not cause an individual fatal infection, any fluid contact with open wounds will lead to irreversible contamination of the individual.

Those bitten experience the following symptoms as the infection progresses, ending in death:
 * Dizziness
 * Weakness and fatigue
 * Fever
 * Delirium/hallucinations
 * Chills
 * Nausea/vomiting
 * Pale skin
 * Diluted pupils
 * Soreness
 * Fluid discharge
 * Spontaneous aggression or anger
 * Fainting
 * Hair loss and missing scalp pieces
 * Dehydration
 * Coughing up Blood
 * Internal hemorrhaging
 * Organ failure

Reanimation
Anyone that dies from a zombie bite will eventually reanimate, unless the brain is destroyed before possible reanimation.

Physiology
Zombies so far are shown to just roam around mindlessly, unless faced with a human in front of them. They can detect smells, and have good hearing. Zombies also do not feel any pain, and can survive without any vital organs or limbs, save for the brain.

Behavior
A reanimated body responds to stimuli such as light, scent, and loud noises. Oddly, even if the head is separated from the body, as long as the brain is intact, the head will still attempt to eat anything within reach. The body of a zombie does appear to be truly dead, which means that it does not feel pain, has no reflexes, and wounds to it will not heal; its rate of decomposition slows drastically but does continue.

Disposal
Because a zombie is derived from a human form, it is limited physically by many of the same constraints that a human has. But because a zombie is, by definition, dead, it slowly rots and decays like other dead organisms. Over time, flesh and muscles deteriorate, and it becomes less and less formidable.

They are only truly killed by destroying the brain. Because a zombie is derived from a human form, it is limited physically by many of the same constraints that a human has. But because a zombie is, by definition, dead, it slowly rots and decays like other dead organisms. Over time, flesh and muscles deteriorate, and it becomes less and less formidable.

Intelligence
Though zombies retain a physical resemblance to the living, cognitive similarities are almost non-existent beyond low-level functions. Zombies have enough intelligence to walk upright, to use their bodies to break objects, and to climb around or over somewhat small obstacles such as chain-link fences. Zombies can ascend and descend staircases, albeit very clumsily and slowly.

They are not hunters, however, and take no concern in alerting their victims or trying to hunt them with intelligence, always seeming to roar, grunt, and growl whenever they are stimulated. Zombies seem to be drawn to noise (such as that of a gunshot), presumably because they attribute the source of the noise to be caused by potential victims.

Zombies also tend to form groups and stick together, and mimic the actions of other zombies, giving them a mob mentality. This can lead to zombies forming "herds," large hordes of zombies are far more dangerous and aggressive than smaller groups.

They lack any remaining speech capabilities, and can only moan, grunt, or wheeze, as well as roar and scream when alerted. Zombies are not shown to be able to "communicate" with other zombies by any means.

Eating Habits
Zombies prefer to eat anything dead or alive: animals and people. Though, they have not been shown to eat each other.

Characters That Turned
The following is a list of characters from The Walking Dead that have all died and reanimated as a zombie.


 * Leon Basset
 * Jenny Jones
 * Bicycle Girl

Prominent Victims
The most notable characters killed by zombies are listed below.


 * Leon Basset
 * Jenny Jones

Trivia

 * It has been confirmed the works of George A. Romero were never made, and thus zombies do not appear in fiction.