- "Taking you easy? No, you are the ones who're taking me easy. My name is Sebas. The one who gave me my name is the strongest warrior. The master I serve is a Supreme Being. But, I can see it’s no use talking about him to lower creatures such as yourselves. I grow tired of talking. Let’s finish this."
- - Sebas Tian to Six Arms.
Sebas is 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 from their chain of command. He originally served as Nazarick's last line of defense alongside the Pleiades in the 9th Floor, to give time for the guild, Ainz Ooal Gown to prepare for their final stand in the Throne Room.
Sebas Tian has the appearance of an elderly butler and he is dressed gracefully in his traditional black uniform. Sebas's hair is entirely white, just like his immaculate beard. He has visible wrinkles on his hollow face, which makes him seem gentle in appearance, but his eyes are as sharp as an eagle's. However, in the manga his beard is longer, his shoulders aren't as broad and his face is also older.
Like his creator, Touch Me, Sebas Tian has a great deal of personal justice. Unlike many other denizens in Nazarick, he does not completely despise humans or see them as inferior creatures. Instead, he believes that some humans have a good nature and it is the duty of the strong to protect the weak. Ugly natured humans disgust him and he will not hesitate to kill anyone who dares to oppose Nazarick.
Due to the conflict in their personalities, he and Demiurge do not appear to get along well, as their characteristics are polar opposites.
Sebas Tian was created by Touch Me. He and the Pleiades served as a last line of defense against intruders. However, because he is unlikely able to stand against enemy players who managed to come this far, his only real purpose was to distract the invaders until the guild members of Ainz Ooal Gown are able to fully prepare for their final stand in the throne room.
The Undead King Arc
- Main article: The Undead King Arc
Sebas was the second person Momonga spoke to when he first arrived into the New World. His orders were to immediately survey the area around the Nazarick's surface above the 1st Floor after it was transported into the New World. He finds that the tomb is surrounded by grassland and the skies are completely normal, much to Momonga's suprise as he later reports this to all whom are present including the Floor Guardians on the 6th Floor.
After Momonga returned from his surveying of Nazarick, Sebas lectured him sternly for not bringing his personal guards along. The butler stood by Momonga's side the entire time as he was experimenting with the Mirror of Remote Viewing, and praised his master when he successfully figured out how to control it. However, when Sebas saw the massacre occurring in Carne Village, he couldn't help but feel obliged to help the villagers at the sight of the situation.
The Bloody Valkyrie Arc
- Main article: The Bloody Valkyrie Arc
While Ainz had been masquerading as an adventurer, Sebas and Solution Epsilon have been ordered to disguise themselves as wealthy and influential humans to gather information. Particularly, the roles they played were an elderly butler and a spoiled and rich noble.
At the Shining Golden Pavilion, Sebas acted as Solution's elderly butler while Solution acted as a spoiled rich girl. She then makes loud complaints about the food, giving everyone a bad impression of her. However, Sebas apologises for her behavior and offers to pay for everyone's meals. As they prepare to leave, Zach, a hired hand, attempts to delay the departure with a few excuses. Sebas sees through his treachery, and allows him to finish whatever he needs to do while their bags are being packed.
As the carriage goes on its way, Sebas engages in a discussion with Shalltear, who has joined them on this segment of their journey. The two of them talk about her relationship with Aura, the old creators, the mystery of the 8th Floor, and the job Shalltear was assigned to do. When the bandits targeting them have been lured out and slaughter, Sebas and Solution split off from her.
The Men in the Kingdom Arc
After buying some magic scrolls, Sebas walks through an alley as a shortcut. While walking by a pub a sack is thrown out of the door. The sack turns out to have a woman inside of it beaten badly and looking close to death. The woman grabs Sebas leg and looks at him. After some men comes out from the door, they get into an argument with Sebas saying that the woman belongs to them, Sebas asking the woman if she wants to be saved. After getting a reply, he takes her home with him after scaring the men away.
Upon Sebas return to the mansion he is questioned by Solution Epsilon why he would take a human back to their place. He answer that she should be useful for their cover once healed to act as a servant in their mansion. Sebas orders Solution to heal the woman and that she will not report this back to Nazarick. After she is healed the woman reveals herself as Tsuare having been a slave and rescued by Sebas, she gladly accepts becoming a maid and strongly imprints on him. Afterward, a group of guards lead by Staffan Heivish and Succulent turns up accusing them of involving in slave trafficking and demanding them to pay a heavy fine and turn over Tsuare to their custody. Sebas quickly realizes that these are corrupted guards working on behest of the criminal group that he saved Tsuare from. After getting the guards to leave without a fight. Sebas decides to go out and crush this criminal group to prevent any further trouble.
Sebas notices that someone is following him and finds a boy being beaten up by a group of men. Sebas got into a fight with them and easily beat up the leader of the group and scared the men away. Sebas meets Climb, who asks him to teach him how to fight. Sebas test Climb's determination by swinging his fist with the intent to kill, Climb barely manages to move out of the way by overcoming his fear. He was interrupted by Brain Unglaus, who is watching them. Then they are ambushed by assassin but they're able to defeat them. They interrogate one of them and tells them, they were sent to kill Sebas by Succulent of Six Arms. Sebas along with Climb and Brain raided the brothel and capturing Cocco Doll and Succulent. Sebas returns to the mansion and finds Solution not in her disguise but in her full battle maid equipment promptly stating that Ainz Ooal Gown is waiting for him.
Sebas is being questioned by Ainz and to test his loyalty, he must kill Tsuare. He tries to kill her seriously but block by Cocytus, stating that Sebas has proved his loyalty. After that Sebas is relieved that Tsuare became a maid of Nazarick and also under the protection of his master's name. After the mission to gather information and the process of moving all the wheat from the storage in the Royal Capital is finished, Sebas and Solution prepare to return to Nazarick. However, Sebas finds out that Tsuare is kidnapped by Eight Fingers and contacts Ainz about the kidnapping of Tsuare.
Sebas then meet up with Climb, Brain and Lockmyer by coincidence. They exchange information of their situation. Concluding their discussion, they decided that Brain, Climb and Lockmyer would search for Tsuare while Sebas goes to the arena where four of Six Arms were waiting for him. Sebas arrives there as they are ready to execute him, but kills them in less than twenty seconds. He then leaves Solution to kidnap the audience present in the arena and goes off to search for Tsuare. Sebas enters the area with a rescued Tsuare. He tells Zero that killed all his subordinates. Zero uses his strongest attack on Sebas but he withstood it easily and kills Zero with a heel drop kick. After bidding farewell to Climb and Brain, Sebas carries Tsuare with him and returns to Nazarick with Solution.
The Invaders of the Large Tomb Arc
- Main article: The Invaders of the Large Tomb Arc
Sebas Tian and Solution are present in the Throne Room of Nazarick, where Ainz personally thanks the two for their efforts in gathering information. Ainz offers Sebas a reward, he initially declines, but gives into his master's insistence, requesting that he be given clothes for Tuare. Not wanting to acquire the high-grade materials from Ainz's collection, he asks if he be allow to go with Tuare to the Royal Capital in the Kingdom to shop for some clothes for her.
The Magic Caster of Destroy Arc
- Main article: The Magic Caster of Destroy Arc
Once Jircniv Rune Farlord El Nix was dismissed from the Throne Room of Nazarick, he along with the Floor Guardians convened before Ainz Ooal Gown to discuss Ainz's next phase of world domination.
The Pleiades Day Arc
- Main article: The Pleiades Day Arc
Sebas was present alongside Yuri Alpha as they observed Tsuare's maid movements. Though Yuri commented that the human was growing tired and request she take a break, Sebas insisted that her training continue. His reasons for pushing her was to prepare Tsuare's role as head maid in E-Rantel. Due to such as important role being bestowed, he did not wish to embarrass Ainz.
The Craftsman of Dwarf Arc
- Main article: The Craftsman of Dwarf Arc
According to Ainz, Sebas was currently providing administrative support in E-Rantel, with Tsuare as his assistant.
- In the Web Novel, Sebas was not asked by Momonga for help on readjusting the Remote Viewing Lens.
- In the Manga, Sebas has a longer beard than in the anime.
- It is said that Sebas's appearance is the spitting image of how Touch Me looks like in real life.
- Sebas believed that it is wrong to cast out a pitiable existence simply due to possibilities of risk.
- Sebas mentioned that if he had to obey anyone's orders without question, it would be his creator Touch Me.
- (To Momonga): "The person responsible for gathering us all. Compassionate and refused to abandon us until the very end, in order to stay behind and fight alongside us."
- (To Davernoch): "There is only one being who can use that title. The one who stands above all. How dare some lesser undead like you use it."
- (To Edström): "To fight even after losing your head. I applaud your fighting spirit."
- (To Peshurian): "What is this. You were talking about slashing through dimensions."
- (To Malmvist): "You only need to admit that I am stronger than you are. What a troublesome person. If you wish to, keep thinking so."