The protagonist of the series who played Yggdrasil as a non-human race. He inhabits the new world in his skeletal lich form, having achieved the highest possible level in Yggdrasil he finds himself still imbued with the same incredible powers and abilities. As an undead race he finds that he no longer requires sleep or sustenance in the traditional sense and has lost empathy for the living beings of the world. While travelling the world incognito he assumes the identity of a heavily armored warrior named "Momon" and quickly develops a reputation, earning the nickname "Momon the Dark Hero".

The NPC overseer of the guild that Momonga helped create and arguably the most powerful NPC residing within the guild. Albedo's character was carefully programmed by another player, but before the shutdown Momonga made several alterations to her personality that he felt would not cause harm as the game was going to close. The changes stuck when the game world shifted and Momonga found Albedo had fallen madly in love with him just as he had entered. Albedo takes the form of a tall, pale skinned woman with an ample bosom, a pair of inwardly curved horns, long black hair and a pair of black feathered wings.

The NPC Floor Guardian responsible for the First, Second, and Third Floors of the guild. Shalltear is a vampire who takes the form of a young looking girl in a gothic black dress, with white hair and blood red eyes. It is rumored that she alone could stand toe-to-toe with Albedo among the Guild's NPCs and she often clashes with Albedo over her affections for Momonga because of her love for him as well.

The NPC Floor Guardian responsible for the 7th Floor of the Great Tomb of Nazarick,the Commander of the NPC defenses and the 2nd in command of the Floor Guardians. He is the creation of Ulbert Alain Odle.

The NPC Floor Guardian of the 5th Floor in the Great Tomb of Nazarick. He was created by the 'supreme being' Warrior Takemikazuchi as the embodiment of the word "Warrior".

NPC dark elf and one of the twin Floor Guardians on the 6th Floor in the Great Tomb of Nazarick. She is the older twin sister of Mare Bello Fiore and was created by Bukubukuchagama. As a beast tamer and ranger, she is capable of controlling magic beasts and is a master of guerrilla warfare.

NPC dark elf and one of the twin Floor Guardians on the 6th Floor of the Great Tomb of Nazarick. Mare is the younger twin brother of Aura Bella Fiora. Alongside his sister, he was created by Bukubukuchagama.

The NPC Floor Guardian on the 8th Floor of the Great Tomb of Nazarick.

The NPC 4th Floor Guardian of the Great Tomb of Nazarick. Unlike the other Guardians, it is not a Custom NPC but a bonus won by Ainz Ooal Gown.

An Area Guardian of the Treasury and the financial manager of Nazarick. He is responsible for the upkeep of Nazarick and Ainz Ooal Gown. He was created by Momonga himself.

The head butler of the Great Tomb of Nazarick with several manservants and other butlers under his command. He was created by Touch Me. He is also the leader of the Pleiades Six Stars.

Although he is not one of the Floor Guardians, his power closely rivals theirs. In a way, he is independent of their chain of command. He originally served as Nazarick's last line of defense alongside the Pleiades on the 9th Floor, to give time for the guild, Ainz Ooal Gown, to prepare for their final stand in the Throne Room.

The vice-captain of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Yamaiko, one of the three female members of Ainz Ooal Gown.

A werewolf battle maid and a member of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Beast King Mekongawa.

A doppelgänger battle maid and a member of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Nishikienrai, one of the original nine founders of Ainz Ooal Gown.

She is also known as Nabe, a magic caster and Momon's adventurer partner of Darkness. As an adamantite ranked adventurer, she is one of the most powerful adventurers in the Sorcerer Kingdom.

An automaton battle maid and a member of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Garnet.

A slime battle maid and a member of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Herohero

An arachnid battle maid and a member of the "Pleiades Six Stars," the battle maid squad of the Great Tomb of Nazarick. She was created by Genjiro.

An Area Guardian and the Head Maid of Nazarick. She is also one of the few NPCs sympathetic towards humans.

The leader of the Lizardman Tribes and chieftain of the Green Claw Tribe. He is the older brother of Zaryusu Shasha. He was also amongst the few surviving lizardmen who fought against Cocytus himself.

A white albino lizardman and the acting chieftain of the Red Eye tribe.