The ensemble cast of My Hero Academia stretches to dozens of characters, nearly all of who shape the story in their own ways. From school students to their teachers, from heroes to villains and everything in between, the anime deals with a number of intersecting storylines and personal arcs.
On the other hand, there aren't too many characters that are important enough to be considered central to the narrative, but those that are really do make a splash. Here are the scenes in which each main character truly shines.
Izuku Midoriya — Stands His Ground Against The Sludge Villain
Although he is the protagonist, Izuku's defining moment comes when he chooses, at great risk to his own life, to save his old friend. Having been captured by the Sludge Villain, Bakugo's unrefined Explosion Quirk is completely useless. Izuku notices a cry for help masked in Bakugo's face and thinks nothing of running in to the rescue.
This moment is especially important given that All Might himself laments about his lack of power, and it reminds the Pro Heroes what a real hero looks like. Also, it's important to note that Izuku doesn't have any Quirk at this time.
Tomura Shigaraki — Unleashes The Full Force Of His Decay
Tomura starts the months-long process to transfer the All For One Quirk into himself but is interrupted by the Pro Heroes before it can be properly completed. This results in him having far less control of his new ability, as well as allowing All For One to begin controlling his so-called protégé.
At the same time, Tomura's personal Quirk, Decay, receives a significant upgrade in terms of range and effect. He can now vaporize entire cities, as he does when he vaporizes Jaku General Hospital and the surrounding township in an incredible display of force.
All Might — United States Of Smash
There are many memorable scenes involving All Might, several of them charmingly comical, but the one that stands out the most is his final stand against his archnemesis. When All For One taunts him for losing his Quirk and threatens to hurt the people that All Might has spent years protecting, it triggers something primal in the Number 1 Pro Hero.
All Might receives a subconscious message of encouragement from Nana Shimura, leading him to gather up the fading embers of One For All and launch the most powerful attack seen in the story currently: the United States of Smash.
Lemillion — Abandons His Dreams To Save A Little Child
Lemillion's Permeation Quirk is a complex one, but he has mastered its nuances to such a fine degree that he can simultaneously take out multiple opponents — even if they are as strong as Class 1-A. Lemillion wants nothing more than to "save a million people," which makes his sacrifice all the more meaningful.
Instead of letting little Eri be struck by a Quirk-destroying bullet, he takes the shot in the back while continuing to comfort his charge. Thankfully, Lemillion's good deed is repaid later in the manga.
Eri — Forms A Symbiotic Bond With Deku Against Kai Chisaki
Eri spends most of her childhood being tortured at the hands of Kai Chisaki, better known as Overhaul, after he takes up guardianship of her.
While facing her adoptive father in his final battle, she latches onto Izuku and activates her Rewind Quirk, which works effortlessly to balance out the damage caused to Izuku's body by One For All. This combination makes short work of Overhaul and hints at the powerhouse that Eri is likely to become in the future.
Shoto Todoroki — Uses His Fire Powers In The U.A. Sports Festival
Shoto cannot abide his father, Enji (or Endeavor), because of his treatment of their family in the past. He vows that he will never activate the fire part of his Half-Hot Half-Cold Quirk, thereby denying his father the satisfaction of having a child who can surpass him.
Despite his hatred, Shoto's resolve is weakened, and ultimately broken, when Izuku convinces him that he is the only one who has control of his Quirk and that using it would not be a tribute to Endeavor in any way.
Endeavor — Apologizes And Makes Amends With His Family
Interestingly, Endeavor comes to terms with his earlier crimes and begins to patch things up with his family. He makes amends with his wife and daughter, but his two sons give him the cold shoulder for quite some time.
The fact, however, is that the first step to forgiveness is making the attempt to seek it, and Endeavor struggles onward despite considerable backlash. He tries his best, and when he fails, he tries again. The dinner party at the Todoroki household is an excellent example of Endeavor turning over a new leaf.
All For One — Announces Himself As The Next Demon Lord
At the conclusion of the Paranormal Liberation Arc, it is revealed that several prisons are attacked by various Nomu, setting free several villains (and, most importantly, those who would make the best minions for All For One.)
The main antagonist finally escapes Tartarus, telling Tomura Shigaraki, Spinner, and Dabi that he is destined to be "a more perfect demon lord." A chilling statement delivered by the man with the power to make his words come true.
Ochaco Uraraka — Leaps To Save Izuku After The Blackwhip Mishap
In the class battles, Izuku is confounded by a new aura inexplicably exploding from his body which is later revealed to be Blackwhip, the Quirk of Daigoro Banjo, another One For All holder.
In the process, he bravely asks his friends to leave the area in order to avoid getting caught, but Ochaco is having none of it. Right before Blackwhip tendrils completely swallow Izuku, Ochaco grabs him and requests Hitoshi to take control of Izuku's movements. If she hadn't done so, it's likely that several students might have been injured.
Katsuki Bakugo — Has A Massive Change Of Heart In The Middle Of Battle
Bakugo makes no attempt to hide his revulsion of Izuku, not to mention his growing displeasure at realizing that One For All is certain to surpass his Explosion. In the fight with Tomura and All For One, Bakugo displays an uncharacteristic concern for Izuku pushing himself beyond the limits of his experience.
At the moment that All For One activates his Rivet Stab at Izuku, Bakugo blocks the attack with his own body and begins falling to the ground. This scene changes everything between the two boys.