Khun Aguero Agnis (쿤 아게로 아그니스, Khun Ahgehro Ageunis; or "Kun Agero Agnis" or "Khun Aguero Agnes") is a C-Rank Regular from Khun Family, and is often referred to simply as "Khun". He is a best friend of Twenty-Fifth Baam, one of the main protagonists of Tower of God.
He is one of many "defected sons" of Khun Eduan. He was expelled from his family because his older sister failed to become one of Zahard's Princesses. He teamed up with Baam and Rak and passed multiple tests with them. He was assigned the Light Bearer position and showed clear talent in the field. He is a highly cunning Regular, who manipulates rules of tests to suit his needs.
SIU has stated that he feels attached to Khun as he feels "Khun is very human".
He holds some political power and relationships within his family.
It is implied that Khun entered the Tower to gain authority and political power (권력과 힘). This is later confirmed when he expresses his desire to take Khun Eduan's position as a family head. This gives off the impression that he is insecure about his exile from the Khun Family.
Khun once raided Khun Eduan's treasure room prior to entering the Tower, an unprecedented action even from members of the Khun Family.
SIU has stated that Khun is his least favourite character. This is because he is from a good family and is rich and smart, but also because the plot tends to get complicated and hard-to-follow when he's around.
However, SIU gave this answer when asked who his favourite character was, which may imply that Khun is actually his favourite character.
SIU has said (perhaps jokingly) that Khun spends a lot of time on his hair and that he is known as the hair straightener prince.
His background will be revealed throughout the story.
Though Khun has only been seen in the position of Light Bearer, SIU has hinted that he is capable of other Positions (such as Spear Bearer as he inherited the Ice Spear affinity from his father), but he chooses to be a Light Bearer because he enjoys commanding others.
The earrings that Khun wears may be made of Suspendium, as it is shiny and blue and someone tried to steal it. 
It is stated that he is slightly older and taller than Khun Ran.
He likes eating Western foods, and he doesn't eat a lot.
Khun started acting like an adult ever since he was a little kid. This in turn leads him to bear an inner desire to return to childhood. Khun is an ironic character in that way. We will be exploring Khun more deeply in the Khun Family arc which will come later on.
He was raised quite harshly even among the Khun Family members.
He will go through a lot of transformation in his power in combat.
SIU: Khun is a character who is pretty good at utilizing or applying his ability once he awakens it.
"SIU: Some readers want Khun to actually fight. But I wanted to give him powers that fit to Light Bearer, such as Enna Core or freezing. Khun is not strong enough to fight Rankers yet. I hope you look forward to his development." — SIU
(On the Second Floor) "I will not be ruled. I make my own rules. That is the mindset of a ruler."
(First taking interest in Baam) "It is natural for you not to trust me. But- I don't care about the rules anymore. Because- I've decided to go up the Tower with you."
(Bluffing to Hatsu) "Our town has earring fever. Everyone has at least 5-6 earrings and, it's in style for all animals- land, water, and air- and even more, all things, to have earrings. That's the general trend."
(Speech to his teammates) "I will climb the Tower and become the head of the Khun Family. I will climb the Tower and inherit Khun Eduan's position. Because I need that power. I'll promise you. If I become the Khun head, I will give you anything you want. In exchange for that, I only expect one thing from you guys. Become the fence that protects Rachel. Always help her, treat her kindly, and approach her 'pretending to be a friend'. But, always remember. Never give her sympathy. Don't think of her as a friend. So that one day, you will be able to turn your back on her cries when told to do so. Detest her. Because she is the girl who killed my most precious friend."
(Thinking while telling his team their jobs) "Suspecting that Rachel killed Baam, such a thing is too cruel. So this task should only be carried out by the cruelest of us. Sorry... Baam..."
(To his assassin) "The reason I'm a Light Bearer isn't that I'm weak at close range. It's because I like giving orders."
(Often says this when he deals with his teammates' childishness) "This is driving me nuts..."
(To Ja Wangnan) "If you keep trying to save everyone like this, you might lose them all. You should see the difference between your wish and the reality."
(To Ship Leesoo) "Parties always begin when games are over. No one knows who is gonna be smiling in the end. This rule and the game are our only chance. And for us to win, the game has to start."
(To Rachel) "You surely haven't changed a bit. You still hide your true thoughts, not looking around you and only go after what you want. You are such a "Sly Woman"."
(To Rachel) "Dream on. If I tell Baam everything you have done so far, do you think he will still see you that way? You are not a star, but just filthy trash. And Baam will soon find that out."
(To Rachel) "Gosh, you really have not changed at all. Being so despicable and being unable to do anything by yourself. You always need someone else's help cause there is nothing you can do alone."
(To Boro) "I never do frantic last-ditch efforts that are meaningless. Cause it's not practical at all. I only pursue practical interests."
(To Hwa Ryun) "I believe that you wouldn't have chosen a path that would harm Baam. That's why I'm just waiting like this. If it was the crocodile, he would have jumped into that room right away... But if something does something does happen to Baam from this incident, I'll probably never be able to forgive myself. Regretting believing you foolishly who is a FUG Guide. If things really turn out that way I would try to bring Baam back to life no matter what. Like that Daniel guy... even if I'll have to side with the devil."
(Talking about Dann to Rachel) "You can't do anything on your own. You don't even know how to walk tall and proud on your own. And that's why you stabbed his leg when he was already down. Your two legs are so lousy and weak to the point where you were even jealous of the legs of someone dying. You can't even catch that small sweetfish in a water tank on your own for sure. Because you are so incompetent to that point."
(To Baam after he's back from the rice pot) -- "How sad.. Trying to get more powerful by yourself. When I look at you sometimes, it worries me that, you would just wander off and leave us someday. So at least, tell us when you go somewhere. So that I can chase anytime." (#309 -- S2 Eps.229).
(To Evan Edrok about Baam) "When you think about it, life itself may not have any real meaning, you know? Is being obsessed with breathing & blood flowing through your body really living? In order to find meaning for me being born & living, don't I have to find something more important than that? If something comes up where I have to put my life on the line to go with it, what meaning would the rest of my life have if I were to miss that? Right now I feel like the end of the world will come if Baam isn't here."
(To Rachel) "I told you. You can't catch it. Never in the future as well, you won't be able to have everything in your hands. Because whatever you try to get, I will take them all from you. You have not improved at all in that time. I truly think that God is fair. Cause even if you have two healthy legs, if your soul is all rotten on the inside, he won't let you run fast no matter what."
(To Baam) "Isn't it better being human? Well, I don't completely understand you, but it doesn't look like very much fun being a God who just lives for everyone's else sake. You are a human being anyway. So what's wrong with saving someone you want to save? You may have to treat everyone equally if you were really God. But you are human. That is your power. So you have to decide how to use it yourself."
(Talking about Baam to himself) "Maybe I'm the reason that's slowing Baam down. I'm the one who is falling behind and struggling to go after it. Because I kept believing that they were all meaningless to me."
(Talking to himself) "I don't want to go through a struggle without any hope. What I need is conviction!!"
(To Baam's sworn enemy on the hidden floor) "Isn't it natural for Baam to want to kill you? Neither Baam nor we like seeing Baam looking that. Baam isn't like that because he wants to be. You are a fake. You are just a slayer candidate created by FUG at their will who is different from the real Baam's appearance, power and behaviour. Just get lost. To us, you are nothing more than a nasty ghost."
(Thinking to himself) "Honestly, I'm not sure if I can take another step. My heart feels like it's about to explode. I used to hate this stupid showdowns, but now I don't really mind them. The thing that keeps me going is knowing there are other people in the same mess with me."
(Korean Pronunciation) Kun Ah-geh-ro Ah-geu-ni-seu