Ainz Ooal Gown, formerly a human salaryman, is the Guild Master of Nazarick. He appears as an imposing skeletal Overlord in ornate robes, holding a legendary staff. Internally, he panics about maintaining a god-like facade to avoid disappointing his loyal subordinates. His undead body suppresses emotional spikes, keeping him calculating and fiercely protective of his home. In combat, Ainz is a supreme magic caster specializing in deadly instant-death spells and dark necromancy.

Albedo serves as the Overseer of the Floor Guardians, managing administrative tasks in Nazarick. She appears as a stunning, white-dressed succubus with black wings, though her true form is a massive armored demon. Her personality is completely dominated by an intense, obsessive love for Ainz Ooal Gown. In battle, she functions as the ultimate tank, possessing the highest defensive stats among all the NPCs in Nazarick to easily deflect lethal blows.

Shalltear Bloodfallen is the guardian of the first three floors, known as the Catacombs. She is a True Vampire who looks like a beautiful young girl in lavish gothic clothing, though her face turns monstrous from bloodlust. She is highly prideful and open about her romantic feelings for Ainz. Shalltear is widely considered the strongest guardian in terms of one-on-one combat, combining physical spear strikes with lethal divine magic.

Gargantua is the massive guardian of the fourth floor, which consists of an underground lake. Unlike the other guardians, Gargantua is a strategic-class stone golem that was gifted to the guild by the game's system. Because it is a mindless construct, it has no ego, personality, or thoughts of its own. Despite its lack of intellect, its immense size and raw physical power are completely unmatched, allowing it to easily crush massive armies.

Cocytus is the insectoid guardian of the icy fifth floor of Nazarick. He has the appearance of a massive, four-armed warrior covered in spikes and frozen blue ice. He lives by a strict samurai code of honor, valuing martial skill and loyalty above all else, which makes him stand out among his malicious peers. As Nazarick's premier weapon master, Cocytus can wield multiple weapons simultaneously to shred any enemy who dares challenge him.

Aura Bella Fiora is the energetic co-guardian of the sixth floor's massive amphitheater. She is a dark elf girl who cross-dresses as a boy, a trait designed by her creator. Aura has a loud, tomboyish personality, frequently teasing her twin brother Mare while acting as the dominant leader of their duo. She is a legendary beast tamer who commands an entire army of high-level magical creatures, using her speed and bow attacks to support them from afar

Mare Bello Fiore is the second co-guardian of the sixth floor, working alongside his twin sister Aura. He is a young dark elf boy who wears traditional girls' clothing and possesses a timid, easily frightened demeanor. However, this fragile outer appearance hides a deeply cold, detached ruthlessness when dealing with outsiders. Mare is an incredibly high-level druid who specializes in massive, wide-area earth magic capable of wiping out entire armies in seconds.

Demiurge is the cunning archdevil who guards the seventh floor of Nazarick and acts as the defense commander. He looks like a sharply dressed businessman with glasses and a silver tail, but his true nature is pure, sadistic evil. He is a tactical mastermind who frequently interprets Ainz’s casual remarks as profound strategies. In battle, Demiurge relies on his sharp intellect, summoning powerful demons and using a unique voice control skill to command weak foes.

Victim is the bizarre guardian of the eighth floor, which is the most heavily fortified zone in Nazarick. It looks like a one-metre-long, pink floating angel fetus with halo rings instead of wings. Despite its strange appearance, Victim is incredibly polite and speaks in an ancient language. It has incredibly low combat stats because its primary purpose is to be sacrificed, triggering an inescapable movement-restriction debuff that cripples invading forces.

Sebas Tian is the Head Butler of the Great Tomb of Nazarick, leading the Pleiades Battle Maids. He appears as an elderly, refined human gentleman dressed in a spotless tuxedo, masking his true nature as a high-level Dragonoid. Unlike most of his cruel peers, Sebas possesses a deeply righteous heart, frequently going out of his way to rescue and protect helpless humans. In combat, he is a devastating unarmed brawler, utilizing lightning-fast martial arts and immense physical power.