|Allegiance||Ainz Ooal Gown|
|Headquarters||Great Tomb of Nazarick|
|Light Novel||Overlord Volume 1|
|Manga||Overlord Chapter 1|
|Anime||Overlord Episode 1|
Floor Guardians (階層守護者) are a group of NPCs, who manages the defense of their own floor and they have the highest authority of all NPCs in the Great Tomb of Nazarick.
As the Supreme Being's chosen elite NPCs, the denizens of Nazarick show proper respect to the Floor Guardians for their immense authority and terrifying power.
Floor Guardians roles were similar to 'stage bosses' of a dungeon. Each of them manages the defensive system of their own floor. For that reason, all of them have the highest authority among the NPCs, and most of them (except Victim) are very powerful level 100 NPC. After the teleportation, they closely serve the guild master Ainz Ooal Gown. Now given more freedom and additional duties, they have been slowly gathering resources and monsters to strengthen Nazarick.
The Undead King Arc
- Main article: The Undead King Arc
Momonga, the last of Forty-One Supreme Beings, sensing a disturbing change in the state of the world summons the Floor Guardians to the sixth floor. At the Amphitheater, with exception of Gargantua and Victim, the Floor Guardians have gathered. Here they submit their absolute loyalty to Momonga.
The Bloody Valkyrie Arc
- Main article: The Bloody Valkyrie Arc
During the rebellion of Shalltear Bloodfallen, the Floor Guardians gathered in the tenth floor of Nazarick to discuss how to deal with the situation.
The Lizard Man Heroes Arc
- Main article: The Lizard Man Heroes Arc
The Floor Guardians convened in the throne chamber of Nazarick. Cocytus appeared before his master and his fellow Guardians to answer for his failure in annihilating the Lizardmen Alliance. The Floor Guardians witnessed Cocytus plea to spare the lizardmen, and proposed conquering them instead. With the persuasive argument from Demiurge the petition was accepted with the full support of the Guardians.
The Two Leaders Arc
- Main article: The Two Leaders Arc
It is obvious that floor guardians (except Victim) have their own high combat ability, yet there are still NPCs that are stronger than the floor guardians in the Great Tomb of Nazarick. For example, the most powerful NPC of Nazarick is Rubedo, and it is confirmed that some area guardians optimized in battle are stronger than relatively weak floor guardian.
Among the floor guardians, Shalltear is the strongest floor guardian, and Mare can compete for first and second place with her, following the mentioned of Sebas.
- They have personal bodyguards with the level 75 to guard them when they travel outside of Nazarick.
- Similar to how nobles pride themselves of their bloodlines, the Floor Guardians take pride and dignity to being personal creations of the Forty-One Supreme Beings.