Ainz Ooal Gown

Ainz Ooal Gown (アインズ・ウール・ゴウン, Ainzu Ūru Goun) is one of the main characters of Isekai Quartet, and the protagonist of Overlord. Originally a salaryman named Suzuki Satoru in the year 2138 until his favorite MMO YGGDRASIL shut down and he found himself stuck in a world similar to the game, making him the isekai character in his universe. He is the one of the Supreme Beings and leader of the Great Tomb of Nazarick, and titled the Sorcerer King of the Sorcerer Kingdom. In the Isekai Quartet World, he is a student of Class 2 and its Vice Representative.

Appearance
Ainz Ooal Gown has the appearance of a undead skeleton. From his original world, he wears his usual royal gowns that consist of black robes, golden edges, and two large shoulder-like supports with floating red orbs.

Personality
A wise and powerful king who is beyond merciful, cruel to his enemies, and a hero...The personality he displays to his fellow Guardians, whom he sees as children. While he appreciates them all, he finds them to be a bit stressful and tiring with their praise, and is glad they're now seeking to make friends with others. As a result of this school-life experience, it allows him the opportunity to be a normal person, particularly with Tanya alongside Subaru and Kazuma.

Like from his original Isekai World, Ainz would often think to himself to his surroundings and the various experiences he faces while still overall trying to keep his Overlord persona.

He sees this new world as good for nothing but not necessarily bad, and finds interest in his other classmates. Taking pride in his power and willing to even help his fellow Isekai on Field Day protecting them.

On Test Day, he shows a willing to cheat though only because of the high expectations on him and his own embarrassment in not knowing the answers. Upon seeing the Goddess Aqua willingly cheat, he instantly became ashamed of himself and stopped his spell. He also shows surprise against those who show no reaction toward his great powers. Tanya, Subaru, and Aqua being those three.

Plot
He is sent to the world of Isekai Quartet after sitting on a Mysterious Button after it teleported under him.

Powers & Abilities
As a Level 100 being on YGGDRASIL, he is an insanely powerful Magic Caster. He is able to learn alot of powerful spells on his arsenal. Not only is that the case, he has powerful subjects by his side, on topped of his critical thinking and high IQ.

Magic: As a master magic caster from his world, Ainz Ooal Gown is capable of utilizing many powerful spells from YGGDRASIL. The spells he shown so far in Isekai Quartet are:
 * Unnamed Spell (Most Likely Weather Control, a 6th Tier Spell): Ainz summons many magic circles, then a blast shoots in the sky, and after a certain time, the weather changes into snowy. He used it on Season 1 Episode 5, as his Talent on Show and Tell.
 * Oddly enough, Yuri Alpha, a Pleiades Battle Maid, was able to change the weather in a single snap in Overlord III Episode 9. It's most likely Ainz used many magic Circles as an aestethic.


 * Greater Teleportation (7th Tier): A teleport spell where he is able to teleport at a huge area.


 * Fly (3rd Tier): As per namesake, he is able to fly and hover with this spell.


 * Undeath Army (7th Tier): When together in mass, they are resilient enough to withstand an attack from the Mobile Fortress Destroyer. Like the undead from Konosuba they are drawn to Aqua, and like the Demon Beast in Re:Zero they can be drawn by Subaru's Return by Death's penalty.


 * Unnamed Aura Vision: He was capable of seeing the powerful curse 'Return by Death' within Subaru.

Despair Aura: One of his skills as Overlord which allows him to instill Fear onto others.
 * Body of Effulgent Beryl (10th Tier): A spell that reduced the effectiveness of bludgeoning attacks against its subject while it was in effect, and it could completely negate one instance of bludgeoning damage after it was cast. This spell is powerful enough to repel the Mobile Fortress Destroyer from Kazuma's world.
 * Fireball (3rd Tier): A 3rd tier spell that allows the user to shoots out a big ball of fire that burns its target.
 * Time Stop (10th Tier): Like the name says, time stops, except for the user. Aqua, Natsuki Subaru, and Tanya von Degurechaff are immune to this effect.
 * Nuclear Blast (9th Tier): A spell able to create a powerful explosion. He is able to combine this move with Megumin's Explosion, making the move more potent.

Energy Detection: He could gauge the amount of power from Tanya's own spell stating it to be above 8th Tier magic.

Emotion and Sexual Drive Suppressor: A unique feature by being a undead where his emotions and sex drive are suppressed.

Purification Weakness: Despite his overall great power, Ainz is susceptible to certain purification techniques like Aqua's Turn Undead which was very effective against him to his surprise. This weakness is also most likely related to his weakness affinity to Holy elements as a Undead in his world.

Inability to Digest or Sleep: As an undead, he doesn't need to eat or sleep. However, he sometimes misses eating, especially when he was given chocolates.

The Guardians
His 'children' as he calls them. He does his best to guide them and always tries to help them out. And while grateful to them, he finds them slightly tiring from their views of him. Also a bit embarrsed by Albedo's and Shaltears affections toward him. Still, he considers them family and is glad they're reaching out to make new friends in this world. However, he still shares his overall embarrassing relationship with Pandora's Actor where Ainz denied being Pandora's Actor's father despite being his creator.

He felt bad that he couldn't eat the chocolate some of his fellow Guardians made for him.

Pandora's Actor
Created on his Chunibyou-phase, he is the embodiment of Ainz's past self, which embarrasess him on his day, to the point where he doesn't like to deal with him due to the Actor's antics.

Tanya von Degurechaff
Like Kazuma, he guessed Tanya was from a war world. Originally Tanya thought of him as Being X and wished to face him. Though immediately he was able to convince her he wasn't, and the two learned they were both people originally from Japan and were former salaryman. They soon became good friends but he is somewhat fearful of her were it not for his emotion suppressor. Regardless, his positive relationship with Tanya shows he's willing to cooperate and assist Tanya such as during the Sports Festival. As a result, Tanya also now looks to Ainz's ability in high regard. He is also shocked when she's immune to Time Stop magic.

Satou Kazuma
He is on decent terms with Kazuma. The adventurer helped him out when Aqua attacked and when Raphtalia also almost attempted to attack him.

During physical examination, Ainz made a bet on the teenager, "I'm curious to see if Kazuma has the skills to pull this off". Ainz added, "Rumor is, you have the highest luck of anybody at the school. Let's test that".

Aqua
After being attacked by Aqua by her Turn Undead Spell, he puts his guard around her for how she was able to harm him so easily, finding how unbalance the power scale is in the Isekai-Quartet World. He finds her annoying with her purification attempts yet is still kind enough to defend her from Tanya's wrath. When Aqua reveals that she's aware of Ainz's original identity as a human from Earth, he was surprised by her deduction. He is one of few individuals who seems to be aware of Aqua's claim as a Goddess. He admits she is a goddesses after she proves immune to his time stopping spell.

Megumin
He respects Megumin's powerful explosions magic, saying that it was on the 8th or 9th tier on the world of YGGDRASIL. Later on a dodgeball game, Ainz teams up with her to combine their respective explosive spells, resulting on a powerful blast.

Natsuki Subaru
In the opening they both laugh awkwardly around each other. He finds the boy very interesting as he notices a strange dark aura around him which makes him somewhat aware of Subaru's Return by Death. Despite this awareness, he decides not to explore the matter any further. He apologizes for touching him, and is on decent terms with him. He also figure out Subaru's strong mental fortitude, a feature that Subaru has from the constant mental stress he faces from his world, after seeing him unfazed when Tanya unleashed her powerful magical aura. He points out Subaru's hypocrisy of his Battle Maids as he has two Demon Maids around him. During the Sports Festival as fellow teammates, the two develop enough trust where Ainz is willing to listen to Subaru's quest when he thought of a plan. He is surprised Subaru is immune to his time stopping magic.

Reinhard
He finds his powers to be utterly absurd, despite himself being absurdly powerful.

Naofumi Iwatani
As a comparison to Subaru, Ainz found the young man to be perfectly normal. After he and Kazuma learned about Naofumi from a demi-human girl, they found that Naofumi was the same young man they saw earlier and Ainz was amazed at how Naofumi protected his two companions including the demi-human girl.

Ainz was the one of the male students that Naofumi and Vanir took physical examinations of.

Raphtalia
When the demi-human girl saw the undead person, her first instinct was to draw her sword. With Kazuma's help, Ainz was able to talk her into cessation of hostility. After the boy and the demi-human girl explained to each other, he and Ainz helped her look for a hero named Naofumi.

Trivia

 * He is the first to deduced another character (Tanya) is from another world.
 * Ainz is notable the only one to identify or be aware of a Isekai character's true identity and abilities from their respective universe (Tanya's past and former identity, Subaru's Return by Death, and Aqua's identity as a Goddess).
 * Aqua is able to deduce he is from earth as she sent people to other world before.
 * Ainz is the only Isekai protagonist not to have died in any way in both his original world or original Isekai world. He's also the only Isekai non-human protagonist unlike Subaru, Tanya, and Kazuma.