Baam, (To Yu Han Sung): "You told me that being like I am is strange, but to me, you're a person who can't even find a single thing that's precious in that huge pile of garbage. I don't care what others say. I will climb the tower and if all of you aren't a bunch of liars, you better prepare what I wantup there."
Rak Wraithraiser you turtle.
Anything Rak does, it will be awesome, even if he loses, or looks silly.
Ship Leesoo, after hearing a Ranker declare that anyone who can't pass his barrier has been choosen to simply fail, says Screw Destiny and pushes his way through the Shinsoo barrier through pure willpower.
Most of Koon's schemes when they come together.
Yuri mopping the floor with Ren (even though it is quite green and slimy afterwards, she really was made for the great outside).
Viole fighting Mule Love, a ranker, as an equal.
Viole and Horyang's Big Damn Heroes moment in the Untrustworthy Room test, and subsequently, Horyang revealing his One-Winged Angel form to the readers for the first time.
During Baam's fight with Horyang, you see him using the techniques he learned from Love.
Urek Mazino, that's all. Showing just how powerful a ranker in the top five can be, and he wasn't even trying.
A minor belated moment of awesome: Viole managed to put a scratch on Mazino, while Rankers stood no chance. Mazino was impressed.
Not just that. Viole turned his back to an attack that is easily strong enough to kill him in order to protect a little girl. Not only does that show that he meant what he said earlier (that there are things he feared more than death), the scratch showed that Viole didn't give up. Even after giving himself such a huge disadvantage by protecting Miseng, he still thought of a way to successfully land a hit.
Androssi taking on the Bull, which is probably stronger than all the other regulars there, and completely annihilating it. Judging by the fact that she was unable to beat it later on, though, it's entirely possible it was letting her win on purpose, which kind of diminishes the awesomeness.
Later on, Baam killing the Bull with a massive blast of Shinsoo. Yes, Baam defeated the creature that was able to capture Androssi with a single attack.
In chapter 43 Viole says that the water actually strengthened Shinsoo due the weird red exoskeleton which was apparently being held there. So this battle wasn't entirely won on his own power.
In the Devil Of The Right Arm arc, we have Viole and Horyang's fight, though SIU cut it short. Then, we have Horyang versus Ran and Novick.
Although chapter 51 was mostly a Tear Jerker, we do have the legendary moment of Dan telling Rachel to fuck off. It might have had unfortunate consequences for him later but it was still very satisfying in the moment and incredibly badass.
What makes it even more awesome is how unexpected it is. Throughout his time on Koon's team, Dan and Rachel have had little moments together that have hinted that Dan might feel sympathy for her and might not be so willing to betray her. After FUG's plans to kill Koon come to light and Dan is at the mercy of Apple and Micheal (traitors who were paid to infiltrate Koon's team for FUG), Rachel asks them to spare Dan since he hasn't done anything wrong. After all, he was originally kidnapped by Koon and forced onto the team. Dan's response to her next question shows just how awesome he is though. Especially considering he doesn't necessarily do it out of loyalty towards Koon. He refuses Rachel because her behavior, along with Apple and Micheal's, disgusts him.
Rachel: Mr. Dan, let's climb the tower together. From now on, please become my legs.
Dan: If you want to walk, walk with those fine legs of yours. You kicked away two friends with those legs, am I right?
A Meta-related moment of awesome here, but SIU won the award for 2012 Readers Best Manhwa Award, Grand Prize, for Tower of God. Even with that, SIU is filled with awesome for the amount of work he put into TOG, leaving his fans guessing. There is a even a thread dedicated 'Things You Probably Didn't Notice', based on the whole lot of miniscule not-so-obvious details he slips in. How many of you noticed that Viole threw his pocket to Agero before the Hand Of Arlene exploded? Well, if you noticed that ball shaped object you might have mistaken for a piece of debris while everything was blowing up...
Team Leesoo vs Team F.U.G. Sure, they ultimately lost, but they managed to do a pretty good job and put up a decent fight before Viole used his Thorn power.
Viole in the workshop battle, against the fake F.U.G. followers.
Am I still your god?
In one fight Ran completely dissected Anak's personalty and flaws so next time he could draw her into a fight she couldn't, and indeed didn't, win.
Novick has been ambushed by Reflejo, Ron Mei and the two swordsman members of Team Mad Dog and is saved by Horyang who vaporizes the latter two and attacks Mei and Reflejo with enough power to level a portion of the forest. Points to Ron Mei, for having the ability to block the attack and showing she is no air-head.