As a shonen protagonist, My Hero Academia's Deku is inexorably bound to genre tropes—he must consistently and continuously throw himself in the path of danger in order to save lives and make people happy. Although his ambition is overly simplistic, the fact remains that Deku never once hesitates when it comes to rescuing others, especially those closest to him.
Although his initial lack of control over One For All is largely responsible for multiple near-death situations, mastering his inherited Quirk has done little to change Deku's self-sacrificial nature. In fact, it takes a literal horde of people to convince him that he doesn't have to carry his burdens alone.
Manga Spoilers Below
10 Deku Nearly Loses Everything When Fighting Nine
Class 1-A resolves to stop Nine and his henchmen, partially succeeding when they manage to separate the villains (making it easier to pick them off one by one). They learn that their opponents are almost as strong solo, forcing each student combatant to push their boundaries.
Deku and Bakugo team up to defeat Nine, but his Quirks are far too strong even for the overpowered pair to handle. Eventually, Deku decides to transfer his Quirk to Bakugo, allowing them access to double the attack power offered by One For All. Luckily, Deku doesn't lose One For All, which is fortunate because his hero identity means more to him than anything else.
9 He Attacks Stain On Tenya's Behalf
Tenya flat-out lies to Deku and Uraraka, informing them that he has no intention of following his brother's attacker. Instead, he does the exact opposite, leaving him in a rather sticky situation—at Stain's bloodcurdling mercy.
Deku uses his deductive skills to investigate and locate his friend, where he thinks nothing of charging at the Hero Killer with every ounce of force he can muster. It can be argued that both Deku and Tenya would have perished on the spot if Shoto hadn't found them in time.
8 Deku Agrees To Hunt Down The League Of Villains
After Bakugo is abducted using Mr. Compress' and Kurogiri's Quirks, Deku is naturally grief-stricken and instantly blames himself. His friends, Kirishima and Momo in particular, help assuage his guilt but also suggest that they all join forces and root out the League of Villains, rescuing Bakugo in the process.
Despite some minor resistance from Tenya, the group trudges on with their half-baked plan, only to find themselves caught in the crossfire between All Might and All For One. Although Deku's on-the-fly strategizing saves the day, he could have just as easily been killed with his friends.
7 He Nearly Dies During The U.A. Entrance Exam
Deku walks into the U.A. Entrance Exam's facility area with anxiety writ large on his face. He realizes that manifesting One For All so quickly after inheriting it would cause more harm than good, a sensible decision that is ultimately forgotten when he sees that a young girl is in danger.
In order to protect her, a person he has no emotional ties to at the time, Deku annihilates the gigantic robot before it can crush Uraraka. This obviously leads to three of his limbs being shattered, but Deku is thankfully saved when Uraraka triggers her Zero Gravity.
6 Deku Jumps In To Save Bakugo Without Thinking
Deku's heroic nature precedes his Quirk by several years, seeing as he doesn't think twice before leaping into the fiery midst of battle. When he sees Bakugo engulfed by the Sludge Villain, he screams and runs to save his friend, completely forgetting the latter's mistreatment and bullying.
Deku's courage doesn't do much by itself, but it spurs All Might into completing the rescue mission—and he later asks Deku to become the next bearer of One For All.
5 He Attacks Tomura Shigaraki/All For One
During the Paranormal Liberation War in Jaku City, Tomura starts losing the upper hand when the heroes trick him into the path of Endeavor's Prominence Burn. This consequently makes Tomura accept All For One's intrusion, allowing his "mentor" to take part in the fight. AFO immediately resorts to Rivet Stab, but Bakugo blocks the attack with his torso, leaving him severely injured.
To nobody's surprise, Deku reacts in a thoughtless fury and flies at Tomura. As luck would have it, this is where everyone discovers that One For All cannot be stolen by All For One, because the opposite would have meant certain death for Deku.
4 Deku Never Lets Go Of Eri After Rescuing Her
Deku is inconsolable after discovering that he could have technically saved little Eri from Kai Chisaki's monstrous experiments, but he vows never to make that mistake again.
As such, he manages to snatch Eri up right from under Chisaki's nose, denying the villain when he demands to have his "daughter" returned. In addition to his boldness and his Quirk, Deku has significant amounts of luck on his side, given that Eri's Rewind pairs perfectly with One For All at 100%.
3 He Maxes Out One For All Multiple Times
Aside from his battle against Overhaul, Deku uses his Quirk at 100% on multiple occasions. In one notable example, Deku tries to defeat Tomura Shigaraki, pushing the latter to the brink of destruction, but fails when AFO arrives.
In another, he charges One For All to 100% and smashes into Muscular, but this doesn't have the effect he expects. As a result, Deku is forced to utilize 1,000,000% of One For All, a Delaware-Detroit Smash that all but pulverizes Muscular.
2 Deku Insists On Saving Lady Nagant From All For One
Lady Nagant is a fearsome combatant, one that Deku would have had no chance against before acquiring access to his predecessors' Quirks. As it stands, however, the young hero manages to avoid her attacks with surprising ease, and even goes on to push Overhaul away from Nagant's projectile.
Deku pleads with the villain to turn away from All For One's evil ways, which, combined with his nearly sacrificial act, helps sway Lady Nagant towards "the light."
1 He Leaves U.A. To Redirect All For One's Attention
Following the mass breakout from Tartarus, Deku realizes that his best course of action would be to leave his beloved U.A. behind for the time being. Not only is it heartbreaking for him to abandon his friends, but having no access to the school's security measures also puts him in mortal danger.
All Might and Inko Midoriya are naturally nervous about Deku's decision, but he firmly avows that he has no intention of seeing anyone else injured on his behalf.