History Fridge / OnePunchMan

* During Saitama's battle with Cosmic Fear Mode Garou, Saitama appeared to be fully intent on killing Garou, and he even said that Saitama will continue to grow stronger until one of his punches ''eventually'' kills him, implying that he's not strong enough to do so yet... And then God effortlessly kills Garou once he surrenders. This could mean that even at the (current) peak of his power, Saitama is still less powerful than God by a not insignificant amount. Considering [[InvincibleHero his track record so far]], that's not a good look for humanity.

* During the physical portion of the examination, a character remarks with horror that Saitama may have the power of a god residing in him. At first it seems like hyperbole, an exaggeration of the display he put on. Until Genos later explains that "God" is the most extreme ranking that can be given to a threat. A threat that can destroy the planet. Considering the others in the exam would have more knowledge on the workings of the Hero Association, they weren't just exaggerating. They were actually stating that Saitama has planet-busting strength and would be classified as a God-level threat if he went evil!

** Plus, it's not like the countryside is safe. Saitama had to save a fisherman from a monster fish in the countryside, while Sonic had to kill a monster bear that almost killed a hunter. The difference between "city" monsters and "country" monsters is that city monsters are reported right away. A monster in the country can kill lone travelers or entire families and go completely unnoticed. So your options are still in a city and getting caught in it when a monster that can destroy the shelters comes by or still in the countryside and risk being killed without anyone ever knowing. No where is safe for humans.

** We later see Saitama rocket his way back from outer space using some intense flatulence, so... he probably would have been okay!

* King's hero-name sounds pretty on the nose at first, but once chess-motifs are applied, it goes one step deeper. The King-piece in chess is the most treasured one in a chess-game. It's protected by all the other pieces, especially if the King is put in danger by the opponent's pieces. Also, if push comes to shove, it can eliminate the opponent's pieces from the game by itself, but only if the piece in question stands ''right in front'' of the King and not in a checkmate-square, while unprotected by other pieces. The opponent is always deathly-wary about going after the king-piece, due to the high risk of other pieces rushing in to take the assailant out or lose the piece to the King if put on a sacrificial spot. Marking how the King-piece is both the ''weakest'' and yet the ''strongest'' piece on the board, sans the queen.

* Fuhrer Ugly's attacks are all needlessly cruel, disfiguring his targets beyond recognition. This is because of his ugly Ugmon heart, which seeks to make other people ugly just like him. He smashes in Sweet Mask's prized face, and he crushes Tanktop Master's prized body.
* Genos training under Saitama seems pointless considering that, as a cyborg, he can't exactly train to get stronger, and all Saitama can offer is advice and state of mind stuff. But as we see in most of the fights he loses, it's not actually because he lacks power; he tends to get distracted or assume victory too early leaving himself open. His biggest obstacle to getting stronger IS a state of mind issue.
* The fact Sweet Mask and the Ugmons like Fuhrer Ugly turned out entirely differently despite the source of their monster transformations being exactly the same, their deep seated issues over being unattractive, seems rather odd, except there is one key difference: the Ugmons became jealous and hateful due to their appearance, while Amai Mask just resolved to be beautiful on the inside and be a good and just man to compensate for it, and in both cases their new monstrous forms reflected who they were inside, which also partially explains his outlook of BeautyEqualsGoodness. He saw first hand cases of someone becoming beautiful because they were good, while he saw others [[EvilMakesYouUgly become (more) ugly because they were evil]].

** Plus, it's not like the countryside is safe. Saitama had to save a fisherman from a monster fish in the countryside, while Sonic had to kill a monster bear that almost killed a hunter. The difference between "city" monsters and "country" monsters is that city monsters are reported right away. A monster in the country can kill lone travelers or entire families and go completely unnoticed. So your options are still in a city and get caught in it when a monster that can destroy the shelters comes by or still in the countryside and risk being killed without anyone ever knowing. No where is safe for humans.

** Not counting the rock he threw at his head?
*** The rock clearly wasn't an attack to end the fight but a way for Saitama to turn Crablante's attention away from the kid to him.

** Given that Vaccine Man stated that he was created by the Earth to wipe out humanity and Homeless Emperor was only granted his powers from "God" when he decided to give himself back to the Earth through suicide... Yeah, it's not unlikely that "God" and the Earth are related if not the exact same thing and it wants humanity dead. Badly. So badly that it's sending multiple insanely powerful monsters to wipe us out and it's not stopping. In fact, Saitama hitting the moon (making it look like the eye of a god) and Orochi being sacrificed to "God" on the altar in the planet (and the fact that Orochi could use energy from the Earth's core to power his attacks), it seems the Earth and moon are somehow deeply involved in the heroes' and monsters' powers. The situation is only getting worse. Add in the cubes and Blast spending the last two decades or so tracking them down but the monsterification is STILL accelerating out of control despite his efforts... Yeah, humanity is losing this fight. Plus, it's not like the country side is safe. Saitama had to save a fisherman from a monster fish in the countryside while Sonic had to kill a monster bear that almost killed a hunter. The difference between "city" monsters and "country" monsters is that city monsters are reported right away. A monster in the country can kill lone travelers or entire families and go completely unnoticed. So your options are still in a city and get caught in it when a monster that can destroy the shelters comes by or still in the countryside and risk being killed without anyone ever knowing. No where is safe for humans. Add in all the stress, anger, and terror, then you have more people becoming heartless or obsessing over something, anything to get out of their horrible life and, in this universe, obsession turns you into another monster. Just imagine one day your neighbor in the apartment complex turns into a monster and starts killing people, you're going to start distrusting shut-in weirdos, isolating people and breeding more anger, more hatred, and more people are going to try to escape from reality by obsessing over their hobbies or favorite food or their negative emotions... It's a vicious cycle.

* King is touted as the WorldsStrongestMan, feared by most monsters, and even Tatsumaki is hesitant about confronting him. Yet he is ranked 7th among the S-class heroes. This is because he rarely does actual hero work, or to be more precise, he doesn't go out a lot to do hero stuff like slay monsters. And since hero rankings are based not only in strength, but also in accomplishments and popularity, King's rank is simply a testament of how popular he is and of the accomplishments he's done so far.

* One-Punch Man can be abbreviated as 1PM, which is technically the same as 001PM. Now flip over 001PM and you get [=MP100=], the commonly used abbreviation of ''Manga/MobPsycho100'', which happens to be ONE's second most popular work.

* Vaccine Man doesn't get much credit as a monster, being the very first enemy we see Saitama effortlessly defeat. But if you really look at him, you'll see that he was one of, if not ''the'' most powerful monster the Hero Association had ever faced up until that point. His light ball explosions were absolutely gigantic, and he had advanced physical strength and durability that put him a step above the similar monster Homeless Emperor. This is explored in the bonus chapter ''Witness'' in Volume 15, where the chaos and panic caused by Vaccine Man are truly shown. Then there's his transformation - who knows what that could have done. If it weren't for Saitama, he would have been an ''enormous'' threat that likely would have required someone like Tatsumaki to take down.

** It's also terrifying thinking how strong his punches might be. His serious strike ''parted the sky''. And that's only ''after'' it was used to stop a planet-bursting attack, meaning that it's power was considerably lessened. And, if Boros was right, Saitama didn't even strike as hard as he could. But that's not the worst, the worst is that this would still be just ''one'' punch, but his chain of punches is explicitly called "normal multiple punches", implying there's a serious version of that one too...

** Given that Vaccine Man stated that he was created by the Earth to wipe out humanity and Homeless Emperor was only granted his powers from "God" when he decided to give himself back to the Earth through suicide... Yeah, it's not unlikely that "God" and the Earth are related if not the exact same thing and it wants humanity dead. Badly. So badly that it's sending multiple insanely powerful monsters to wipe us out and it's not stopping. In fact, Saitama hitting the moon (making it look like the eye of a god) and Orochi being sacrificed to "God" on the altar in the planet (and the fact that Orochi could use energy from the Earth's core to power his attacks), it seems the Earth and moon are somehow deeply involved in the heroes' and monsters' powers. The situation is only getting worse. Add in the cubes and Blast spending the last 2 decades or so tracking them down but the monsterification is STILL accelerating out of control despite his efforts... Yeah, humanity is losing this fight. Plus, it's not like the country side is safe. Saitama had to save a fisherman from a monster fish in the countryside while Sonic had to kill a monster bear that almost killed a hunter. The difference between "city" monsters and "country" monsters is that city monsters are reported right away. A monster in the country can kill lone travlers or entire families and go completely unnoticed. So your options are still in a city and get caught in it when a monster that can destroy the shelters comes by or still in the countryside and risk being killed without anyone ever knowing. No where is safe for humans. Add in all the stress, anger, and terror, then you have more people becoming heartless or obsessing over something, anything to get out of their horrible life and, in this universe, obsession turns you into another monster. Just imagine one day your neighbor in the apartment complex turns into a monster and starts killing people, you're going to start distrusting shut-in weirdos, isolating people and breeding more anger, more hatred, and more people are going to try to escape from reality by obsessing over their hobbies or favorite food or their negative emotions... It's a vicious cycle.
* The Ninja Village is actually a facility that turns young children into emotionless killing machines for the Underworld. A single day consists of '''72 hours''', only 6 of which are allocated for sleeping. They were kept alive through special drugs, which also prevented them from committing suicide. It almost sounds like they wanted them on the ''verge of death'' at all times... which is a known method of breaking limiters.

* Genos training under Saitama seems pointless considering that, as a {{cyborg}}, he can't exactly train to get stronger, and all Saitama can offer is advice and state of mind stuff. But as we see in most of the fights he loses, it's not actually because he lacks power; he tends to get distracted or assume victory to early leaving himself open. His biggest obstacle to getting stronger IS a state of mind issue.

--> '''Garou:''' The popular will win, the hated will lose. It's such a tragedy.\\

* Vaccine Man doesn't get much credit as a monster, being the very first enemy we see Saitama effortlessly defeat. But if you really look at him, you'll see that he was one of, if not ''the'' most powerful monster the Hero Association had ever faced up until that point. His light ball explosions were absolutely gigantic, and he had advanced physical strength and durability that put him a step above the similar monster Homeless Emperor. This is explored in the bonus chapter ''Witness'' in Volume 15, where the chaos and panic caused by Vaccine Man are truly shown. Then there's his transformation - who knows what that could have done. If it weren't for Saitama, he would have been an ''enormous'' threat that likely would have required someone like Tatsumaki to take down.
** The same goes for Beefcake/Marugori. The guy was so unbelievably gigantic, even dwarfing giants such as Orochi (though his size fluctuates, sometimes being incredibly exaggerated in the anime such as his footprint) and he could destroy entire cities with the mere swing of an arm. He would have definitely required several S-Class to take down.

* Vaccine Man doesn't get much credit as a monster, being the very first enemy we see Saitama effortlessly defeat. But if you really look at him, you'll see that he was one of, if not ''the'' most powerful monster the Hero Association had ever faced up until that point. His light ball explosions were absolutely gigantic, and he had advanced physical strength and durability that put him a step above the similar monster Homeless Emperor. This is explored in the bonus chapter ''Witness'' in Volume 15, where the chaos and panic caused by Vaccine Man are truly explored. Then there's his transformation - who knows what that could have done. If it weren't for Saitama, he would have been an ''enormous'' threat that likely would have required someone like Tatsumaki to take down.

* The Sky King being killed by Melzalgald and replaced with Boros might have been more than just a simple BaitAndSwitch. Since he was the conqueror of the universe, one could consider Boros the true "ruler of the skies".

** Garou comes fairly close to this. He's [[NotSoDifferent one of the biggest parallels to Saitama the series has to offer]] but whereas Saitama wanted to be a hero when he was a kid, Garou wanted to be a monster. Prior to facing Saitama, he was able to defeat every hero he fought, which included more than half the S-Class, and that's without the use of [[OneWingedAngel his final transformation]]. The thing that's more "fridge" than just regular horror is that his HeroKiller title is hyperbole; he never actually killed anyone. If he had actually made an effort to finish off his targets, especially in his "unfair evil" form, every hero except for Saitama and [[CompleteImmortality Zombieman]] would probably be dead.

* The webcomic's [[StylisticSuck artstyle]] might be intentional to evoke the same reaction as its protagonist. It's a good comic, but people who aren't interested ([[HypeAversion or outright avoiding it]]) just look at it and think "there's no way that this deserves this much attention" and might even doubt ONE's ability to draw. Which is exactly the kind of response Saitama gets InUniverse.