Five Rulers

Five Rulers were a group of bosses that originally inhabited the Great Tomb of Nazarick before it was conquered by Ainz Ooal Gown.

Background
The Five Rulers were five powerful monsters that were designated by the Lord of Helheim to protect the five of six original floors of the Great Tomb of Nazarick.

Overlord Prologue Arc
Inside the Great Tomb of Nazarick, the Five Rulers faced off against the newly created guild, Ainz Ooal Gown. However, all six teams of the guild successfully defeated each of the bosses. Due to the guild's success in conquering the dungeon on the first time, they were awarded the rights to the Great Tomb of Nazarick.

Strength
The bosses encountered by the members of Ainz Ooal Gown noted that they had different abilities, appearances, and boss rooms to fight each of them in.

Known Members

 * Pure White Bat: This monster guarded the Underground Lake Floor.
 * Lightning Dragon: This monster guarded the Volcanic Floor.
 * Asura: This monster guarded the Tombstone Floor.

Trivia

 * After a party defeats one of Five Rulers, they must fight against hordes of enemies on the wastelands floors until all the Rulers have been defeated.
 * After Ainz Ooal Gown conquered the dungeon, it is unknown what became of the bosses.