Zombies

Definition
Zombie: A deceased human body that has somehow become reanimated and autonomous, yet no longer has sufficient brain or vital functions to be considered alive or capable of thought.

"These things ain't sick! They're not people! They're dead! Ain't got to feel nothing for them, 'cause all they do, they kill! These things right here!"

- Shane to the group about what zombies are.

"Walking Dead" Zombies
Zombies within The Walking Dead universe are Robert Kirkman's version of George Romero's Night of the Living Dead. Robert Kirkman wrote that "Romero's evolving zombies are his spin. Mine just keep rotting." Kirkman's zombies are relatively weak and unintelligent as individuals, but are dangerous in large numbers, and are the main antagonists within the post-apocalyptic world of The Walking Dead. Zombies out-number humans about 5,000 to 1.

Reanimation
Following classic Romero rules, the dead corpse of anyone that dies for any reason will reanimate as a zombie, unless the brain of that individual is badly damaged or destroyed. When a person dies, the infection they carry reactivates critical areas of the brain that support necessary vital systems, resulting in reanimation. Because only a portion of the brain is reactivated, the reanimated person retains only a physical resemblance to their former self.

According to the CDC's Dr. Edwin Jenner in the TV series, a corpse can reanimate between three minutes and eight hours after death. Some reanimations have occurred faster than Jenner's three-minute benchmark; after being stabbed, Shane Walsh reanimated after less than two minutes and Woodbury resident Michael Coleman reanimated in approximately 45 seconds. Executive producer Glen Mazzara hinted that the time it takes for a corpse to reanimate depends on how full of life the person was before they died.

Zombie Pathogen
Most if not everyone on the planet within The Walking Dead universe somehow contracts a mysterious pathogen that, for reasons unknown, brings the dead back to "life." It is unknown how the disease is spread. There are no known cases of immunity. No treatment exists. According to Dr. Edwin Jenner, the exact taxonomy of the pathogen is unknown (virus, prion, bacteria, or hitherto unknown microbe), and all known attempts to create a cure or vaccine have thus far failed. Jenner's research has been fruitless.

"There is no hope. There never was...  This is what takes us down, this is our extinction event....""

- Dr. Edwin Jenner

The first cases of infection progressed through a state of fever, aches, and internal bleeding, and this illness ultimately was fatal. All brain activity would cease and the body would be clinically dead: no measurable brain activity, no reflexes, and no respiration or pulse. Shortly thereafter, the pathogen would reactivate the brainstem of the dead body, but only the brainstem and not the cerebrum or cerebellum. The person would be dead, literally and figuratively, no respiration, pulse, or higher mental function, driven by subconscious survival instincts only. In this reanimated state, the dead body was able to wander around instinctively trying to feed itself even though it had no digestive or circulatory activity. A reanimated body responds to stimuli such as light, scent, and loud noises. Oddly, even if the head was separated from the body, as long as the brain was intact, the head would still attempt to eat anything within reach. The body was truly dead, which meant that it did not feel pain, had no reflexes, and wounds to it (apart from those directly inflicted on the brain) did not heal; its rate of decomposition slowed somewhat while reanimated but the breakdown process continued. There is anecdotal evidence that some Walkers retained vestigial elements of memory and personality such as clinging to possessions. A Walker was also once observed to use a brick as a tool, but there has been only one observation and that was in the field.

Robert Kirkman wrote:

"The rule is: WHATEVER it is that causes the zombies, is something everyone already has. If you stub your toe, get an infection and die, you turn into a zombie, UNLESS your brain is damaged. If someone shoots you in the head and you die, you're dead. A zombie bite kills you because of infection, or blood loss, not because of the zombie 'virus.'"

Zombie Bites
Zombie bites do not kill because of the zombie pathogen, but rather the unsanitary nature of their mouths due to diet and decomposition. Scratches cause similar infections for similar reasons. Their mouths and saliva often contain several septic factors, specifically the bacteria: ''[http://en.wikipedia.org/wiki/Escherichia_coli%7CE. E. coli], Staphylococcus sp., Providencia sp., Proteus morgani, P. mirabilis, and multocida''. The rapid growth of these bacteria tends to cause extremely virulent strains that are highly resistant to antibiotics, and most often lethal. It can be assumed, however, that an undetermined number of original "outbreak" cases involved recently-reanimated zombies that were relatively intact and "clean", biting others and still causing infectious deaths, indicating that there is a possibility of the zombie "virus" itself producing lethal, transmittable organisms within zombies upon reanimation.

Symptoms of infection
The first form of the infection was the transmission of the pathogen from an undead host to a living body via bites and scratches. The second form is already contained within all living people, and merely requires the death of the host to activate the zombie condition. The pathogen causing reanimation is not independently fatal and lies dormant within a host until the host dies of another cause. In the case of Walker attacks, the cause of death is generally infection by necrotic biological debris and other infectious agents contained in that debris (for example, saliva from a bite).

Symptoms of this massive and multiple infection include:
 * Fever/Delirium/Hallucinations
 * Chills.
 * Nausea/Vomiting.
 * Pale skin.
 * Dilated pupils.
 * Soreness.
 * Fluid discharge.
 * Fainting.
 * Loss of hair and missing scalp pieces.
 * Dehydration.
 * Vomiting blood.

Because of antibiotic resistance or inefficacy, and extremely fast growth rate of said bacteria, immediate amputation of the wounded limb is usually the most effective method of preventing systemic infection that eventually leads to death. Bites to the neck, head, or trunk are invariably fatal and cannot be treated.

If the wound is not properly cauterized, cleaned, and/or wrapped, however, amputation may not be enough to stop the lethal infection without medicine, and even then, survival rates are not easily estimated, as only one person (in each format) is known to have survived an amputation of an infected limb.

Killing the Undead
Because a Walker is derived from a human form, it is limited physically by many of the same constraints that a human has. But because a Walker is, by definition, dead, it slowly rots and decays like other dead organisms. Over time, flesh and muscles deteriorate, and the Walker becomes less and less formidable. Though unconfirmed, it is assumed that a Walker will eventually decompose on its own until only its skeleton remains. A Walker may be neutralized by severe damage to or removal of part or all of their body below the skull. However, in The Walking Dead universe, they are only truly killed by damaging the brain, a common theme in many zombie variations. A severed Walker head will remain animated and aggressive until the brain is destroyed or eventually disintegrates from decomposition. Detached Walker heads have been observed to remain animated even after long term submersion in water as long as the brain is undamaged. Though they can continue functioning without an intact spine, anything below a point of severing will be paralyzed.

Physiology
It has been demonstrated that zombies don't require sustenance by eating, but have a strong desire to do so. Zombies have the ability to detect scents and differentiate between the living and the dead, and prefer to feed on living flesh. Covering one's self in the scent of decay can act as a camouflage. They can also use sight to distinguish living from dead, although they seem to have poor eyesight as their irises fade and decay, but they make up for it in very heightened senses of strong hearing and smell. They can also determine a human presence by feeling certain cues such as the breathing movements or a heart that is beating at an irregular pace from a scared human.

Other than a mostly intact brain, zombies don't appear to require any vital systems or organ functions to survive, although their ambulatory functions do decrease as their level of decomposition increases.

In "Walk With Me", it is revealed that zombies starve, but at a significantly slower rate than humans. When a living person goes into starvation mode from lack of nourishment, their body begins breaking down fat tissue, followed by muscle tissue and converting it into energy. Eventually, the body will begin breaking down the tissue of vital organs and the person eventually expires when those organs cease to function. In theory, if a zombie cannot find a food source, the zombie pathogen will probably cause a break down of body tissue and convert it into energy even though they are dead, until they basically wither away to nothing.

As with all myths, the precise details can vary by author. This information pertains specifically to The Walking Dead television series.

Intelligence
Though zombies retain a physical resemblance to the living, cognitive similarities are almost non-existent beyond low-level functions, though there are examples of behavior that suggest zombies may retain small fragments of memory of their past lives. 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. In the first season, they are also capable of climbing ladders, using door knobs and display very limited problem solving capability and understanding of simple tools, such as using a rock to break a pane of glass. In "Made to Suffer", a walker is seen putting it's hands up to block an attack by Sasha, indicating that some are capable of defending themselves to a degree. Mostly, zombies are void of any emotional expression and thought, showing animalistic traits of anger and hunger when stimulated. This anger seems to dominate hunger, leading them to yell and grunt at their prey when chasing them or when obstructed from them with no concern for alerting their prey. Zombies seem to be drawn to noise, presumably because they attribute the source of the noise to be caused by possible prey. Zombies also tend to form groups and stick together, and mimic the actions of other zombies, giving them a mob mentality. In "Guts", zombies retain a further animalistic trait within their "herds", appearing to "sniff out" or examine new-coming zombies before leaving them be, as they do to Rick and Glenn, which may indicate that zombies seem to be able to familiarize themselves with their own kind and be cautious of ones they do not recognize. As shown in "Seed", Zombies are also shown to possibly have a predatory instinct of "playing dead", lying inanimate, even after being shot and knowing the living are nearby, only to attack them when they get close, biting Hershel's leg.

In "Infected", we learn that walkers can be conditioned. Walkers surrounding the Prison have gathered at the fences because a so-far unidentified individual is feeding them live rats at night.

Eating Habits
Zombies prefer to eat living flesh: birds, animals, and people. If living food isn't available, zombies will eat meat from dead corpses, unless, in the case of humans, the corpse reanimates as a new member of the undead. Zombies do not digest food. When their bodies are "full", the undigested meat will be forced out through the anus. As zombies are dead, it is assumed that their bodies will continue to rot even if they are well-fed. If no sustenance is available, though slower than humans, zombies will starve, ultimately contributing to the rate of decomposition.

If the zombie loses the ability to feed, they evidently lose the desire to do so - a behavior observed in Michonne's pet Walkers. The presence of many zombies being partially consumed or missing limbs also indicates that zombies, though they seem perpetually hungry, do not always devour prey fully, meaning that, at least for a short period of time, can feel "full" and not want to eat. In the TV series, the Walker that consumed Lori Grimes' body was lethargic, sated and full, and did not attack Rick when he arrived on the scene. Still, they can be driven to attack and consume live prey due to the sheer aggressiveness the reanimative contagion seems to have given them.

This is, of course, mostly speculation and almost no real evidence backs it.

Movement
Compared to humans, zombies have rather limited mobility. Unstimulated, zombies stand still or shuffle around rather slowly. When in this state they are referred to as "lurkers," as they can quickly activate and attack and kill. Some "living" zombies can also be found lying on the ground or in piles of other bodies, often appearing dead until stimulated. However if they are pursuing a possible victim, zombies can move somewhat more quickly, roughly equivalent to a very light jogging pace. Often times zombie mobility can be impeded by an injury sustained before or after reanimation. Injuries often cause a zombie to shuffle awkwardly or even sometimes drag a damaged appendage as they move. Due to limited intelligence, zombies have difficulty overcoming various obstacles. Zombies can ascend and descend stairs, but they cannot do so gracefully or quickly. As zombies do not require sleep or nourishment, they are constantly ready to respond to stimuli even when in their "lurker" state.

Nicknames
While the term "zombie" does exist within The Walking Dead universe, it is seldom used. In the comic book, when Rick's group discover the prison, both Rick and Tyreese discuss how it still sounds funny to use the word "zombie". Likewise, in the Telltale video game, the term is used but very rarely. "Zombie" is never used in the TV series; when interviewed, Lauren Cohan stated that Romero movie zombies never existed in the popular fiction of the TV Walking Dead universe. The characters within The Walking Dead TV series and comic books come up with their own monikers and categorizations for the undead.

The term "zombie" originated with the Haitian practice of voodoo and refers to a person who is reanimated as a slave in the thrall of another person. Those zombies are still clinically alive and can be restored, where the "walkers" of The Walking Dead are in fact dead, not under any control, and cannot be restored.

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' survivors group to refer to reanimated corpses who are not dormant.

Roamers
Roamers are known to "roam" around looking for food. They are the most commonly encountered type of zombies. The term "roamer" is used most frequently in the Comic Series.

Lurkers
Lurkers are the zombies that just sit around playing "dead" until something approaches them and they bite. Lurkers can be the real threat because they can appear to be a dead corpse. One of them was responsible for Allen's death. In the TV series, Hershel had his leg bitten by a lurker and had to amputate it to survive. Oftentimes, lurkers have suffered some type of major injury or are otherwise in some kind of weakened state, preventing them from walking around. The term "lurker" is used most frequently in the Comic Series.

The term "Lurkers" is also used by some in Woodbury.

The Herd
As described by Eugene in the comic book, a herd is when a group of Walkers act with a mob mentality. One zombie might brush his hand on a door knob and another will see this and mistake it as an attempt to get in. Then he will beat on the door to get in, and the first zombie will see this and try to get in. This will spark a chain reaction. An example of this is in the start of the Season 2 finale where a zombie sees a helicopter and follows it to Hershel's Farm.

Biters
Alice, Dr. Stevens' assistant in Woodbury, mentioned that her original group of survivors referred to the zombies as "biters", because, while some do lurk or roam, they will all bite, so to classify them into separate groups was considered a silly practice. "Biters" is what Woodbury call the zombies, as seen in the novel and comic series.

Floaters
Floaters are zombies that became bloated after spending a long period of time in water. One was first encountered by the survivors at the Greene Family Farm in the TV series where it was found trapped in a well. Fearing that shooting the floater might result in polluting the well, the survivors decide to pull it out. This proves to be futile as it gets stuck on the lip and splits in half, the bottom part of its body (and most of its innards) falling back into the well.

Lame-Brains
The term "lame-brains" was first used in the TV episode "Nebraska" by Dave and Tony, strangers that walk in the local bar not far from the Greene Family Farm. It seems to be a broad category for all zombies, equivalent to the term "Walkers".

Geeks
In the TV Series, Daryl, T-Dog, Shane, and Glenn have been known to call zombies "geeks." This name is also used by Molly from the video game. She says she calls them geeks because, just like carnival geeks, they will eat anything. This name isn't used in the comic series. More recently however, the term has been abandoned.

Monsters
In the video game, Chet, Clementine, and Brenda call the zombies, "monsters", Rick also calls the zombies "monsters" once in the Comic Series. In "When the Dead Come Knocking", when Milton and Andrea wait until Mr. Coleman turns, she realizes that Milton’s never seen a loved one turn into a Walker and said: "There is no unconscious mind, Milton. When they turn, they become monsters, that's all. Whatever they once were is gone".

Meat Puppets
This name is used by a Savior. Since he is part of The Saviors, it is presumed that the nickname is a common one amongst the group. The name most likely originated from the fact that the zombies' intelligence levels are very low, so they are just considered mindless puppets of meat.

Empties
When Paul Monroe was saved by Abraham and Michonne as he was sleeping in an abandoned car, he used the name "empties" to refer to the zombies that were trying to get into the car.

Deadie
The name was used by Albert as he panics after eating Dale's leg, whom was bitten. The term is also used in the The Walking Dead Video Game by Andrew St. John when recalling them getting caught on the electric fence surrounding the St. John's Dairy Farm.

Creepers
The name is used by Merle Dixon in "Walk With Me". Merle uses this term when he is about to kill multiple Walkers.

Swimmers
This name is used when Dale and T-Dog encounter a bloated zombie trapped in the depths of a well while living at Hershel's farm. The exact quote is "Looks like we've got us a swimmer."

Dead Ones
This is used several times to describe a group of zombies.

Eaters
This term is used by Daryl Dixon to describe the zombies during the earlier stages of the outbreak in The Walking Dead: Survival Instinct.

Ghouls
This term is used by Tyreese in the Comic Series (Issue 7) while talking to Rick about how he fears more the living than the "half-rotten ghoul trying to eat my flesh." Carley from the video game also calls them this when Lee asks if Doug saved her. During Survival Instinct, Kessler says that he locked himself up from the 'damn ghouls'.

Psychos
This name is used by Daryl Dixon in The Walking Dead: Survival Instinct, during his talk with a cop called Jimmy Blake, who is hiding in a shelter on the roof of a building.

Wanderers
This term, though not said as much, is used describing unseen or roaming walkers.

Abomination
Used by Merle Dixon in the Survival Instinct game.

Creepy-Crawlies
Used by Chuck in the Video Game.

Goons
In Survival Instinct, The remaining Survivors in Oakview calls the zombies, "Goons".

Decays
In The Walking Dead Webisodes: The Oath, Karina calls the zombies "Decays".

Swarms
Used in The Walking Dead Webisodes: The Oath, a small horde is called a "swarm" by Paul and Karina.

Walking Bodies
Gale Macones, in The Walking Dead Webisodes: The Oath, calls the undead, "walking bodies".

FAQ
Q: Can humans ever win, and rebuild civilization?

A: Yes. If somehow humans were able to survive long enough for all the Walkers in the Walking Dead universe to become incapacitated due to decay or outright death, humans could rebuild civilization. However, there is still a possibility that one or a group of humans could die unexpectedly when no one is around. As there is no cure, and everyone that dies reanimates as a zombie, the threat of another zombie apocalypse taking over the world will always loom. Additionally, there is no guarantee that the pathogen would not mutate again and cause a new doom.

Q: Do zombies eat animals? If so, would we see 'zombified' animals?

A: Yes, and No. In the Walking Dead universe, zombies will eat any live creature they can get their hands on. However, animal remains will not reanimate.

Q: Can zombies be killed by fire?

A: Yes, fire can damage zombies and incapacitate them. If a zombie's head is exposed to high heat from a fire, their brains can suffer enough damage to effectively kill them. However, the zombies trapped in the Governor's "Walker pit" when Milton set fire to it using gasoline as an accelerant were still functional despite having the equivalent of third-degree burns over their entire bodies.

Q: Can the victim of a zombie bite be saved by cauterizing the wound?

A: Probably not. This might be possible in theory, but the victim's wound would have to be cauterized immediately after the wound is sustained for the operation to have any chance of being effective. Seeing as the characters in the Walking Dead universe have very limited resources at their disposal, it is unlikely that it would be.

Q: Can zombies breathe? If not, how do they smell?

A: Yes. Though unconfirmed, one would assume that zombies must breathe somehow, as breathing is required to make growling noises, to utilize the sense of smell, and to collect oxygen - a necessary chemical used by cells to produce energy. The logical explanation is, at least partly, that all cranial nerves arise in the brain-stem, including the 10th cranial nerve, which innervates the heart and diaphragm, among other things. Breathing is an autonomic (unconscious, passive, and involuntary) function of the body, so requires no cognitive skill. In theory, then, a zombie's heart might also beat. However, a zombie can still function after sustaining critical damage to its lungs, implying that although zombies can breathe, they do not need to.

Q. Can anyone survive a Zombie bite?

A. Yes, while extremely difficult, it is possible to survive a bite from a zombie if many steps are taken. Such steps could include: Amputation; Frequent antibiotics administration; and bandaging and keeping the wound bacteria free. As Kirkman stated "You don't die from the zombie 'virus' you die from infection or blood loss."

Characters That Turned
The following is a list of characters from The Walking Dead that have all died and reanimated as a zombie. The video game section shows all characters that can potentially turn undead, regardless of player choice.

Comic Series

 * Hannah
 * Jim
 * Shane
 * Shawn Greene
 * Julie
 * Chris
 * Rachel Greene
 * Susie Greene
 * Mike
 * Terry
 * Andrew
 * Christina Haben
 * Mike
 * Penny Blake
 * Scoot Moon
 * Dr. Stevens
 * Otis
 * Caesar Martinez
 * Carol
 * Tyreese
 * Duane Jones
 * Jessie Anderson

Season 1

 * Summer
 * Hannah
 * Jenny Jones
 * Leon Basset
 * Wayne Dunlap
 * Amy
 * Jim
 * Dr. Candace Jenner

Season 2

 * Shawn Greene
 * Lacey
 * Duncan
 * Mr. Fischer
 * Mrs. Fischer
 * Louise Bush
 * Annette Greene
 * Doug
 * Sophia Peletier
 * Randall
 * Shane Walsh

Season 3

 * Sean
 * Lieutenant Welles
 * Erin
 * Penny
 * Michael Coleman
 * Duane Jones
 * Merle Dixon
 * Milton Mamet
 * Many unnamed Woodbury Soldiers

Season 4

 * Nick
 * Eddie
 * Clara
 * Patrick
 * Charlie
 * Many unnamed Prison Survivors.

Webisodes

 * Hannah
 * Judy
 * Palmer's Children
 * Harris
 * Lenny
 * B.J.
 * Karina

Season 1

 * Police Officer
 * Sandra
 * Chet (Determinant)
 * B. Everett
 * Jenny Pitcher
 * David Parker (Determinant)
 * Travis (Determinant)
 * Mark
 * Brenda St. John
 * Duck (Determinant)
 * Fivel
 * Jeff
 * Dr. Walter Ashe
 * Crawford Oberson
 * Stranger (Determinant)
 * Brie
 * Tess
 * Ed
 * Diana
 * Lee Everett (Determinant)

"400 Days"

 * Jerry
 * Danny (Determinant)
 * Justin (Determinant)
 * Bennett (Determinant)
 * Clyde
 * Walt (Determinant)
 * Jean

Survival Instinct Game

 * Jess Collins
 * Lester
 * Hartwell
 * Unnamed Biker
 * Terry Harrison's Wife

Novel Series

 * Bobby Marsh
 * Penny Blake
 * David Chalmers
 * Brenda Stookey
 * Scott Moon
 * Megan Lafferty
 * Mike
 * Christina

Social Game

 * Summer's Mother
 * Jon
 * Summer
 * PFC Jackson

Trivia

 * In Issue 38, Robert Kirkman wrote there is "ONE zombie who's appeared no less than three different times in the book"
 * Michonne kills a walker going into a car with a T-shirt that says, "Youngblood", (a superhero comic published by Image Comics).
 * In the TV series, walkers are shown mainly in "Guts" and "Bloodletting" to run at a jogger's pace, despite the fact that Kirkman has stated in the past that all zombies run at the same (or slower) pace than those seen in the Romero films.
 * It is speculated that the more violent the trauma of a victim (of either a walker or living killer), the quicker they re-animate. This is backed up by Shane rising just minutes after being stabbed in the chest by Rick in "Better Angels", but Amy taking several hours to do so from a bite to the arm and to the neck.
 * In the TV Series, the walkers can apparently use tools. This is shown in "Guts," where a zombie is using a rock to smash open the department store doors. This is a possible nod to the Night of the Living Dead (1968).
 * It is also shown in this episode that walkers are capable of climbing small scale objects such as chain fences.
 * In Season 1 of the TV series, the walkers' eyes were generally gray or yellow, but in the Season 2 webisodes, "Cold Storage" and the TV Series, their eyes are generally gold.
 * According to Robert Kirkman in Episode 2 of Talking Dead, in the world of The Walking Dead, the works of George A. Romero were never made, and thus zombies do not appear in fiction.
 * However, Romero has remarked that the Night of The Living Dead was "basically ripped off from a Richard Matheson novel called I Am Legend." In 1964, I Am Legend was adapted to film as The Last Man on Earth and was arguably the first zombie film ever made.
 * In the Webisodes, it is rumored that terrorists caused the "infection." This is most likely not true, as Kirkman himself never intended to explain the source of the outbreak.
 * The term "Zombies" is never mentioned in the TV series; they are simply referred to as "walkers".
 * Robert Kirkman said, "I think the zombies that survive are maybe a little quicker on the uptake than the ones who don't. I think there is still survival of the fittest, even among the zombies".
 * Walkers are some of the many amputees in The Walking Dead. For other victims, see Amputated Victims.
 * Walkers seem to be somewhat tame-able. As Milton explains to The Governor, "...Take away their arms so they can't grab you and take away their jaws so they can't bite you. Take away their ability to eat, they lose interest in doing so". Examples of this are Penny Blake and Michonne's pet walkers. Additionally, Michonne uses her pet walkers to carry her supplies in the Season 3 premiere.
 * On Talking Dead, Robert Kirkman stated that the makeup used on the Zombie extras in Season 3 is more grey to show further decay.
 * It has been confirmed that the Walkers will return as a larger threat in Season 4. Norman Reedus has stated the directors and producers have introduced a way to make the Zombies "scary" again and that they will pose a new threat to the survivors not seen in Season 3.