Elder Liches (エルダーリッチ) are powerful undead magic casters, capable of commanding lesser undead with their necromancy and casting highly destructive magic.
Elder Lich is a monster that spawns when the corpse of an evil magic caster gains unholy life through sacrificial rituals. Due to their fearsome reputation is known by the New World inhabitants, they see Elder Liches as rulers of the undead and lord of the labyrinth. The objective of an Elder Lich's unnatural life was to master magic they couldn’t use when it first spawned and to attain different skills beyond magic as well.
In YGGDRASIL, there are different types of monsters among the Elder Liches such as the White Counterfeiters. Monsters like these were level 30 and are ranked second within the Elder Lich family. There are also other, palette-swapped monsters in YGGDRASIL, colloquially known as the Red Counterfeiters and the Black Counterfeiters. Moreover, if a player who is a Skeleton Mage possesses a Book of the Dead, then they can use it as a Skeleton Mage to ascend into an Elder Lich with specific conditions required to do so.
In the New World, certain individuals who have died prematurely would be able to spawn into an Elder Lich if their regrets are very high and deep such as was the case of Davernoch. An Elder Lich, at some point in their lifetime, after absorbing enough mana as they can acquire, it can transcend to the undead state of a Night Lich. 
On the other hand, there is an infamous Elder Lich, who haunts the Katze Plains on a Ghost Ship that travels around the fog banks. There is also another famous one which haunts and ruled over an abandoned Castle.
Elder Lich wears an old and luxurious robe that covered its body of rotting skins and bones. It would also hold a twisted staff adorned with gems on its end. Beneath its rotting exterior lies a pair of evil eyes brimming with intelligence. An Elder Lich is shrouded in an aura of negative energy that covers its body like a thin fog, giving off a menacing atmosphere.
Unlike normal undead, an Elder Lich retains its intelligence and is the type willing to negotiate and create ties with the living. Thus, it's capable of complex thought and far more dangerous than other undead. As magic users, they are far more suited to commanding lower-tier undead and attacking from afar then fighting face to face. The highest known ranking of undead they can call forth is the 4th tier.
As a magic caster, the Elder Lich's source of mana comes from negative energy power. As Elder Liches leveled up, they gained a skill that when the undead touched someone, they dealt negative energy damage. However, due to the lacking of physical stats and abilities, it is considered as poorly suited for engaging close combat in melee battles.
On the other hand, there were many many different kinds of Elder Lich. This includes the Elder Lich Iguva=41 that Ainz managed to summon who was only level 22. While the Elder Liches working in Ashurbanipal were nicknamed White Counterfeiters, they were only level 30 and are ranked second in the Elder Lich family. There were other, palette-swapped monsters like these in YGGDRASIL, colloquially known as the Red Counterfeiters and the Black Counterfeiters. The many types of Elder Liches make them a dangerous foe and hard to predict when encountered.
In the Web Novel, it was revealed that with the combined firepower of six Elder Liches, their existences altogether would be enough to topple a small city directly.
- 4th tier Summon Undead
Known Elder Liches
- In both the Light Novel and Web Novel, the prerequisite of becoming an Overlord was to be an Elder Lich.
- Apparently, there is a ritual in the New World that allows one to become an Elder Lich, but the power to ascend or descend (depending on one's point of view) to a lich requires the sacrifice of at least the entire population of a city.
- Khajiit was attempting to turn himself into an Elder Lich by sacrificing the entire population of E-Rantel.
- Elder Lich would be a challenging foe to defeat for a platinum-ranked adventurer team, but it is relatively winnable for a mythril-ranked adventurer team.
- Elder Lich is ranked middle within the hierarchy of the Elder Lich type monsters. While as a Skeleton Mage being the lowest, Overlord being the highest.
- According to Hejinmal, when enough elder liches gather together, they begin to form a mage cabal.
- Momonga utilized the Book of the Dead to ascend into an Elder Lich.
- Albedo has trained Elder Liches to be public servants in the Sorcerer Kingdom.
- Due to being unfamiliar with the term Overlord as a race, many New World inhabitants initially mistake Ainz for an Elder Lich when they first meet him face to face.