Undead

For the two main undead factions, see Forsaken and Scourge.

The undead are former mortals who have died and have had their souls trapped between life and death. They derive power from necromantic magic. Most common examples being zombies or ghosts, undead are typically mindless, bloodthirsty fiends hostile toward any living thing that comes across their path. But some have managed to retain their memories and be who they were in life.

Background
Necromancy and the creation of undead soldiers were invented by the necrolords of Maldraxxus in the Shadowlands who use undead as a militia force to use in defense of that entire plane, should it come under attack. Somehow, their knowledge came to be known by the nathrezim, as well as (and, in some cases, through them) various mortals.

Undead have appeared all throughout Azeroth, they were used as a combat tool during the War of the Ancients when the nathrezim used them to scour the remains of Suramar, and once again during First War when the necrolytes of the Orcish Horde animated skeletal warriors to fight against the humans. During the Second War, the essence of those necrolytes was used to power the Horde's death knights during their creation.

Later, the studies of necromancy took an important role and were used heavily in the Third War when the Cult of the Damned spread the plague across Lordaeron resurrecting the majority of the dead denizens, including sapient races and animals. In modern times, the main groups of undead are the Scourge, the Forsaken, and the Knights of the Ebon Blade.

Undead Forsaken
A great portion of the human denizens of the Kingdom of Lordaeron was resurrected by the plague propagated by the Cult of the Damned. First under the Lich King influence, they managed to get free thanks to Sylvanas Windrunner and the weakening of the Lich King in Northrend. After a civil war led by Sylvanas, the undeath survivors proclaimed themselves as the Forsaken, with Sylvanas Windrunner as their Queen, and vowed to defeat the Scourge and ultimately the Lich King himself.

The Forsaken capital, the Undercity, is located under the ruins of Capital City. It is a place of dark, somber colors but it has inns, forges, and businesses that cater not only to the undead but visitors from the Horde, with whom the Forsaken have allied themselves.

Free will is one of the cornerstones of Forsaken culture, with the great capacity for both good and evil that it entails. However, some undead, especially those who die in combat or under extreme stress and are raised soon after, enter into a violent, frenzied state. Undead in this state are easily manipulated and their rage is often directed at the foes of those who raised them. After the effects wear off, if the risen corpse has not been destroyed, they are given the same ultimatum that other Forsaken are offered: join the Dark Lady or return to the grave.

Each Forsaken member follow their queen for various reasons: fear, loyalty, nowhere else to go.

Undead elves
The majority of undead elves were High elves that were resurrected in the Third War by Arthas Menethil and in the later years by Sylvanas Windrunner herself. There are also some resurrected blood elves for example the San'layn and some death knights. Normally these elves have blood-red eyes and deathly pale skin.

San'layn
The San'layn mostly retain the builds of their still-living kin. However, unlike blood elves, their flesh appears necrotic and, though universally pale, ranges from fleshy pinks and red to gray and light green, and they tend to have either white, blond or dark hair while their eyes have white, green, blue or black glows. Some San'layn have clawed fingers and ears more closely resembling those of a bat; in addition, a few have developed wings and horns.

Biology
There are a lot of different undead but they have some common traits like their skin is deteriorating or if they have hair is normally unkempt.

Some undead have Ichor of Undeath running through their bodies. They bleed this green liquid when wounded, though some have no blood or liquid running through their bodies at all. The majority of undead are in a mindless state, without knowing or controlling their bodies but if the body is kept intact, they could potentially avoid this altogether and live forever. Normally the undead do not sleep as it is not necessary for them but there are cases were they have done it but it seems to only rest their bodies, especially Death knights or Forsaken. Some undeath feel the need to breathe, though they can last at least a dozen days without taking a fresh breath of air, depending of the type of undeath but as they are undead, they don't need air to live Undead are capable of eating, but they don't need to. Some undead can smell.

Being an undead has advantages such as dismemberment not being enough to be killed. Some can also reattach their limbs and joints, or replace their body parts by harvesting and sewing on the body parts of others, eat other humanoids and undead, and drain the life force of others. If you want to truly kill an undead for sure, you have to burn the remains of a destroyed body. The light is known to really cause pain to the undead, but if used with the intention of healing, though very painful, it is effective.

Nature of undeath
The souls of the undead (Forsaken, PC death knights, ghouls, etc.) are imperfectly attached to their bodies; the dark magic that sustains them is a buffer that prevents their souls from properly joining with their bodies. This is why undead feel only faint sensations of pain or discomfort from most physical stimuli, and why the Light is so painful to their existence. The primary exception to this rule are liches, as liches bind their souls to a phylactery and then use the phylactery to generate a physical form; this process is why lich bodies look nothing like their mortal bodies, and also why you have to destroy a lich's phylactery to truly kill them.

Despite all this, there exists at least one account of someone becoming undead through the power of the Light: Calia Menethil.

Aside from their affliction, some undead also suffer from an addiction to terrible vices. Death knights, for example, possess an addiction to inflicting pain. If death knights do not regularly inflict agony upon another creature, they begin to suffer wracking pains that could drive them into a mindless, blood-seeking hysteria. Zombies and Forsaken have a hungering for living flesh and San'layn have been known to consume blood.

Generally, most enslaved undead are tormented and restless by their subjugation. Some welcome it if it grants them the benefits of eternal life. Many undead who are sentient enough to understand their circumstances appear emotionally dispassionate if not melancholy. The most known emotions that the undead seem to emote are remorse, pity, or rage.

Record of undead emoting positive emotions are rare, though there are reports, however, that some Forsaken have slowly experienced a sharpening of their dulled senses of touch, smell, and so on, as well as an increase in the flashes of positive emotions that have otherwise become so rare since their fall into undeath, when influenced by the Holy Light. The drawback, however, is that they also become disgusted with themselves and are likely to increase attempts at their own self-destruction; for regaining these senses would force the undead to smell their own rotting flesh, taste the decay in their mouths and throats, and even feel the maggots burrowing within their bodies.

Some of those that freed themselves from the Lich King's grasp are tormented by memories of the unspeakable horrors that they committed as mindless Scourge agents and are driven into madness or consumed by regret, whereas others embrace their new condition and may go on to indulge in their vile vices. Others don't even remember their time as a mindless slave of the Scourge and so bear no emotional trauma from it at all. Thought the person might be traumatized by their experience as an undead, once released their soul will be judged by the entirety of their existence, and, as such, they might still reach a positive afterlife.

Characteristics in World of Warcraft

 * Cannot be skinned, except for certain undead animals that would otherwise be classified as beasts (i.e.: bears, boars, wolves, etc).
 * Generally are unaffected by mind-affecting spells, like fear, sleep or mind control, however, priests can use Shackle Undead to temporarily imprison monsters and paladins can use Turn Evil which works just like a fearing spell. This does not apply to player characters of the undead race, which are technically classified as humanoid, for purposes of game-balance.
 * Can be tracked by Hunters.
 * Death knights under the effect of Lichborne are considered undead.
 * Death Coil (death knight ability) can heal them, assuming they are of friendly allegiance to the death knight.

Corporeal
Corporeal undead are average corpses or body parts reanimated by the plague or necromancers, or are various body parts stitched together into abominations.

Skeletal
Skeletal undead are skeletons animated by magic.

Incorporeal
Incorporeal undead are ghosts and spirits of the dead.

Independent undead
Independent undead are undead who maintain their own free will. Not all undead from Azeroth fall under the auspices of the Scourge. Some undead resisted the command of the Lich King or his minions, while others arose through individual circumstances. Although they have no direct ties to the Scourge, such monsters are no less dangerous. Despite being free of the Lich King's influence, some independent undead still choose to serve the Lich King.

Notes and trivia

 * Tears are not possible for an undead.
 * Some may be able to become drunk. This, however, is debatable as the only known source is Delvar Ironfist, who was an Arms Warrior in the Warlords of Draenor beta, and his written dialogue remained unaffected when he was changed into a Blood Death Knight.
 * Even the dead can feel the kick of Undercity "Skull Shocker".
 * The Forsaken male player character claims to be colorblind due to undeath.
 * For game balance, Forsaken players are classified as humanoids for gameplay reasons because, in a PvP setting, they would be massacred with Exorcism, Holy Wrath, Turn Evil, and Shackle Undead, but they would also be immune to other CC such as Polymorph and Fear. Forsaken were classified as undead in the World of Warcraft beta, but it proved to be too problematic with PvP balance. Many Forsaken NPCs are also considered humanoid.