Undead

Undead (アンデッド) are creatures that have come back to the land of the living after dying and are found both in YGGDRASIL and the New World.

Background
In YGGDRASIL, undead was one of the many races a player can choose to be. Moreover, such race is divided into different subspecies according to their racial level, allowing players to further evolve beyond it. This goes along well with the right classes specifically that are befitting for someone who was an undead. A Necromancer for starters was a class that allowed one to turn a corpse into an undead as their own slave.

However, the quality of the undead produced can vary depending on the species of the corpse especially ones in the New World. The best corpses were those of powerful beings like dragons, while human corpses could become zombies and skeletons. This was shown, when an undead player such as Ainz is able to turn a mere human corpse into the form of a Death Knight. Amidst their ranks are also Skeletal Dragons. Other than these undead, there are also some of the Dragon Lords in the New World who may possibly be one according to Zesshi Zetsumei.

For Ainz, he is able to spawn an undead out of thin air by using one of his many abilities as Overlord, a high-tier race. Yet the undead created were only able to stay in the New World temporarily since it wasn't done with a corpse or any parts of its body, which create a permanent undead. Even mid-tier or higher-tier undead monsters can spawn a weaker undead through the person killed by them. Depending on the undeads' abilities like Crypt Lord or Overlord, they are also able to make their own weak undead minions stronger than normally was supposed to be while controlling them.

On the other hand, the undead are looked upon as monsters that possess an undying hatred for all living creatures. The undead are considered to be the enemy of all living beings. Yet, there are few exceptions to this idea in which Ainz Ooal Gown and Davernoc, who doesn't see it the same way they do, but was still indifferent to them nonetheless in terms of not being able to show emotions physically. Despite Yuri Alpha being an undead, she doesn't seem to bear any ill hatred towards the living and regarded some of them with kindness instead. Also, the same could be said with Evileye, an undead who works in a group like Blue Rose consisting of humans.

Although the undead possesses hatred against the living, some of them are able to somehow suppress it and reach a mutual understanding with the living to some extent. Certain sentient undead are even capable of suppressing their hatred in order to negotiate. If the living were the ones who try to offer negotiation first, then it would usually end up turning out to be a bad trade. But if the undead were to initiate the first offer or negotiation, there had once been instances of people obtaining ancient items that had been made with now-forgotten knowledge. Whenever Ainz issues mental commands over the weaker undead, they won't be able to easily attack the living out of their nature unless it was ordered to do so by their master.

While so, the undead do not age, so they would continue ruling the land for all eternity until it was defeated. Unlike the dragons' own growth rate, high-level undead are not the type to grow in bodily might. They could instead accumulate knowledge and experience constantly over time. From that point of view, the undead might be even stronger than dragons. When a group of weaker undead gather in one place, stronger undead are then created after a certain period of time passes by. For example, a Death Knight spawning in the Katze Plains.

In the New World, it seems there are legendary tales recorded and passed down about the undead. One being the Soul Eaters, which devoured the souls of the living. While another case being the Wriggle Pestilences, which spread disease. Additionally, there are mage cabals which gathered many undead around a core of Elder Liches for instance. And then there was Guphandera Argoros, the undead dragon that lurked in a mountain of the dead and is a user of psychic-type magic. Not only that, but this also includes the Astral Rippers, masses of shadows which stalked the Valley of Shadows, and so on.

Basic Undead Race Traits

 * Critical Hit Invalid
 * Dark Vision
 * Doubled damage by Fire
 * Energy Drain Invalid
 * Food, Drink, and Breathing are Unnecessary
 * Ineffective Mental Function
 * Necromancy Resistance
 * Physical Penalty Resistance
 * Poisoning/Sick/Sleep/Instant Death/Paralysis Invalid
 * Positive, Light, Holy Weakness
 * Recover by Negative Energy
 * Status Damage Invalid
 * Status Penalty in Positive / Holy Area
 * Striking Weapon Weakness

Skeleton

 * Bone Vulture
 * Elder Lich
 * Nazarick Elder Guarder
 * Nazarick Master Guarder
 * Nazarick Old Guarder
 * Overlord
 * Skeletal Dragon
 * Skeleton Archer
 * Skeleton Centipede
 * Skeleton Mage
 * Skeleton Rider
 * Skeleton Warrior
 * Soul Eater

Zombie

 * Blood Meat Hulk
 * Corpse Collector
 * Death Knight
 * Dullahan
 * Eyeball Corpses
 * Freezing Zombie
 * Frost Bone
 * Ghast
 * Ghoul
 * Jack the Ripper
 * Necrosome Giant
 * Organ Egg
 * Plague Bomber
 * Squire Zombie
 * Undead Beast

Death Spirit

 * Astral Reaper
 * Carrion Baby
 * Grim Reaper Thanatos
 * Ghost
 * High Wraith
 * Pale Rider
 * Wight
 * Wraith

Vampire

 * Elder Vampire Bat
 * Lesser Vampire
 * True Vampire
 * Vampire Bride
 * Vampire Princess
 * Vampire Wolf

Unknown Undead

 * Corrupt Dead
 * Crypt Lord
 * Death Cavalier
 * Death Emperor
 * Death Empress
 * Eternal Death
 * Swell Skin
 * Vampiric Dragon Lord
 * Elder Coffin Dragon Lord
 * Guphandera Argoros

Trivia

 * There are numerous undead in the Katze Plains.
 * The Baharuth Empire is conducting experiments to make undead laborers under their control. However, it seems apparent that Ainz is already doing just that with his undead minions, lending them out to the citizens and dealers of his nation for various tasks.
 * Those who died a violent death and the dead who were not properly revered have the highest chance of becoming undead.
 * It is uncertain what causes the spontaneous genesis of the undead, the Baharuth Empire is currently investigating the reason.
 * To prevent the dead from becoming undead, the people of the New World have taken to making proper burials for the dead as soon as possible when death occurs.