My Hero Academia is set in a world where superheroes are relied on to keep the streets safe, and for years on end, All Might, the symbol of peace, was the best at what he did. He wielded the power of One For All, and with it, he could triumph over evil again and again. But he's not so lonely at the top after all.
All Might boasted incredible speed, strength, stamina, and technique during his heyday, but after suffering a serious injury, his power began to decline, and he later handed One For All to Izuku Midoriya. Now, which characters are just over or just under All Might in power during All Might's final weeks as a hero? Many characters are on track to even exceed All Might's power level someday, or already have, while other characters will come close but never truly surpass All Might.
10 close to it: Overhaul, The Matter-Reshaper Villain
The mob boss known as Overhaul has a Quirk of the same name, and what a Quirk it is. Overhaul can reshape flesh or nonliving matter with a simple touch, and on the defensive, he can easily make barriers or heal his own flesh. And that's just the start.
Overhaul can also go on the offensive by blasting apart an enemy's body with his ability, or he can reshape the walls or floor into hardened spikes that impale his foes. Overhaul can also fuse with another person's dead body to add their power to his, or even several at once.
9 may exceed it: Shoto Todoroki, The Fire/Ice Boy
Shoto Todoroki was actually born with a purpose: to rival and surpass All Might, by dint of his incredible combination of Quirks. His father, the fiery hero Endeavor, made sure to marry a woman whose Quirk would complement his own, and he succeeded.
Now, Shoto has the raw talent and firepower to become an incredible hero someday, and he's on the fast track to achieving his father's dream, though Shoto would rather become the #1 hero for his own reasons.
8 close to it: Katsuki Bakugo, The Explosion Hero
The explosive student hero known as Katsuki Bakugo was also born with a favorable combination of his parents' Quirks. He can sweat nitroglycerin and set it off with sparks, thus creating massive explosions with his bare hands.
What is more, Bakugo boasts a sharp analytical mind that almost rivals Izuku's own, and he's fiercely driven to become the best. His Quirk isn't as flexible as Shoto's, but it will take him far, and no doubt he'll become a pro someday.
7 may exceed it: Izuku Midoriya, The Quirkless Boy Who Could
There is a good reason why All Might chose Izuku Midoriya to be his successor. Even without a Quirk of his own, Izuku had the true heart of a hero, with all the courage, resolve, and selflessness needed to be a pro. And then Izuku received One For All to really get things moving.
Izuku has combined his sharp wits and observational skills with his sheer grit and newfound Quirk, and he is rapidly learning how to master his new abilities. It helped a lot when he trained under Gran Torino and figured out the Full Cowling technique.
6 close to it: Fumikage Tokoyami, The Dark Hero
Fumikage Tokoyami is a trainee hero who relies almost entirely on his Quirk known as Dark Shadow. During the day, Fumikage's Quirk has limited power, coming nowhere near All Might's own power level. It's still pretty agile, though.
At night, though, Dark Shadow rapidly grows larger and stronger, to the point that it almost rivals All Might during his waning days. The only downside is that Dark Shadow is also more difficult to control during this state, but Fumikage is working on that.
5 may exceed it: All For One, The Symbol Of Evil
Just the way All Might is the symbol of peace, his nemesis All For One is the symbol of evil, the avatar of greed, destruction, and malice. All For One's Quirk (of the same name) can steal other people's Quirks and move them around, making it a meta-Quirk of sorts.
All For One has gathered and combined so many Quirks, he's like a one-man army, and he can easily stand up to All Might in a serious duel. After all, it was he who inflicted that grievous wound on All Might, to begin with.
4 close to it: Best Jeanist, The Denim Hero
Best Jeanist is a no-nonsense hero who relies mainly on his Quirk, the ability to manipulate denim threads and make them hard and sharp, like steel. In some ways, Best Jeanist is like a spider, minus the sticky quality of spider threads. In exchange, those denim threads are capable of cutting flesh and bone.
In battle, Best Jeanist can create denim webs and barriers to trap his enemies, or he can use those threads to capture a villain and render them incapable of fighting. If pressed, Best Jeanist can simply slash the target apart with those sharp threads.
3 may exceed it: Endeavor, The Flame Hero
By now, All Might has retired as a pro hero, and he has passed the torch to the likes of Endeavor, the flame hero and Izuku. Endeavor was already close to All Might in power, and now, he is even more motivated than ever.
After all, Endeavor must prove that he's worthy of being the #1 hero, and he would suffer great embarrassment if he failed to live up to All Might's reputation. He's strong already, but it's likely that Endeavor will keep powering up and truly eclipse All Might in the near future.
2 close to it: Hooded Nomu
The hooded Nomu that appeared near the end of Season 4 was Endeavor's first big challenge as a pro hero, and like most other Nomu, this creature was a lab-grown horror with more than one Quirk at its disposal.
The hooded Nomu had a muscle augmentation Quirk, a flight Quirk and transforming arms, among other abilities. This creature's power level was astonishingly high, and it took all Endeavor had to crush it.
1 may exceed it: Mirio Togata, The Permeation Hero
Mirio Togata was born with the ability to turn part (or all) of his body intangible, so matter would pass right through. Through hard work and experience, Mirio learned to use this ability to dodge all enemy attacks and pop out of the ground to take his enemies by surprise.
That, combined with Mirio's incredible melee skills and sharp intuition, adds up to a pro hero who could almost certainly rival or exceed All Might's power someday. Mirio is a third-year student, but with his Quirk, he was stronger than most pros already, and he could easily become stronger still. If he obtained One For All, he would definitely exceed All Might's power level before long.