Main Characters | Hero Association (S-Class Heroes) | Villains and Monsters (Monster Association) | Others
Voiced by: Yuuki Kaji (Japanese), Erik Kimerer (English), Rick Loera (Latin American Spanish)
A ninja with super speed who hires himself as a freelance assassin. After a humiliating defeat by Saitama, Sonic declares himself his unofficial nemesis and hounds him for the opportunity to avenge his defeat.
- Amusing Injuries: The first time he fights Saitama, he's defeated via a Groin Attack. In their second fight Saitama smashes his face into the ground so hard that in the extra page it's shown that it left an imprint in the concrete. In a special chapter later on, Saitama defeats him with another Groin Attack, this time accidentally elbowing him in the groin.
- Anti-Villain: Primarily an antagonist but he's just as likely to fight a human villain or a mysterious being if it serves his best interests. More so in the third OVA where he's portrayed sympathetically and aptly described as "complicated".
- Assassin Outclassin': He's a Professional Killer, and his primary target is Saitama. While he was never actually hired to kill Saitama, in their first encounter Sonic mistook him for a Paradiser, who he was tasked with disposing of.
- Axe-Crazy: At times. When Sonic recognizes an opponent as his rival, he does whatever he can to initiate the battle, such as causing massive property damage and endangering the surrounding citizens in order to get Saitama to fight him.
- Bishōnen: Sonic is a slim young man with a feminine face, long black hair tied up in a topknot, and large grey eyes.
- Blood Knight: He's positively thrilled when he comes across an opponent who can actually be a challenge; he immediately realizes that Saitama isn't his target, but doesn't care as long as he gets to fight someone that powerful.
- Butt-Monkey: Nothing ever goes right for him.
- Card-Carrying Villain: Declares himself as one during his second encounter with Saitama in order to goad the latter into fighting him. This works much better than expected, as Saitama was in the middle of searching for a villain to defeat in order to prevent him from losing his hero status due to inactivity.
- The Chew Toy: A Running Gag for Sonic is that with every confrontation with Saitama, he is beaten in a humiliating way. First time was being punched in the groin, second time was being karate chopped on the head from behind and slamming into the concrete making a mark where he landed, the third time got his ultimate technique destroyed by one of Saitama's Super Move "Serious Series", the fourth time (in a special chapter) Saitama elbowed him in the groin while his vision was impaired and the fifth time he stepped in some dog poop, causing him to slip and get hit by his own exploding shuriken.
- Close-Call Haircut: During his fight with Genos, Sonic's hair was cut short by the former. It also counts as a Traumatic Haircut, as said haircut pissed him off.
- Clothing Damage: Gets his clothes torn in almost every fight he's in.
- Curb-Stomp Battle: No points for guessing who wins in his fights against Saitama.
- A Day in the Limelight: The third OVA is centered around his training after Saitama defeats him for the first time.
- Department of Redundancy Department: His name. Lampshaded by Genos.
- Determinator: The man simply will not give up on his quest to defeat Saitama. He knows when to quit and come back later, but that's about it. He is even willing to transform himself into a monster by eating a Monster Cell if meant gaining more power to beat Saitama. Unfortunately for him, Gale Wind and Hellfire Flame fail to mention that he needed to eat the Monster Cell raw, but since Sonic cooked it, the Monster Cell was rendered inactive and he only got an upset stomach.
- Flash Step: He can do this thanks to his super speed.
- Full-Frontal Assault: Being forced to take off his clothes to escape a monster doesn't seem to faze him. Genos thinks he's weird.
- Giving Them the Strip: When the Sea King tries to crush him in his fist, he abandons all of his clothes in a last ditch effort to escape.
- Good Colors, Evil Colors: Black and purple. He usually appears wearing a tight black bodysuit and a long purple scarf.
- Groin Attack: Accidentally runs his crotch directly into Saitama's fist in their first encounter. In the anime, they break out a We Are Experiencing Technical Difficulties card to cover his horrific scream.
- Highly Visible Ninja: While he is capable of stealth, he always announces his presence to his opponents, particularly to Saitama. He gets away with it because he's fast enough that he can kill most enemies before they realize what's happening.
- Jerk with a Heart of Gold: In the third OVA, he helps a baby boar by killing a giant snake that tries to eat it and befriends an old man named Frank. He even goes and names the baby boar "Ino", spends the rest of the episode with it in his training, and gives some advice to Frank to help the old man defeat his arch-enemy.
- Lightning Bruiser: Sonic speed means there's a lot of momentum behind his attacks, even without factoring in his various weapons.
- Long-Haired Pretty Boy: Until his hair was cut short, but remains a bishie.
- Mr. Fanservice: Murata puts a lot of effort into showing just how tight his suit is.
- Mythology Gag: As a side note, this character also appears in one of ONE's other series, Makai No Ossan (Old Man Of The Underworld), as a flasher who startles people at random in school. This joke is referenced during Genos' first encounter with Sonic during the Sea King story arc.
- Ninja: Of course! He was raised as one. As an experienced ninja, it can be assumed that Sonic is a master of ninjutsu and has knowledge of various deadly techniques. He's displayed multiple techniques involving his incredible speed and weapons.
- Off with His Head!: How he deals with anyone he attacks.
- Overshadowed by Awesome: The series makes it clear that, despite his obsession with the nigh-unbeatable Saitama, Sonic is possibly one of the most dangerous human characters in the series, to the point Fubuki herself notes that he could easily be on par with S-Class heroes if he ever tried. He just picked the exact wrong person to see as a rival.
- Scarf Of Ass Kicking: Until his fight with Genos.
- Slasher Smile: He gets a "child-like smile" on his face when he faces a strong opponent like Saitama. He describes it as a bad habit.
- Smug Super: He will always boast about how untouchable he is because of his Super Speed to his opponents.
- Stalker Without a Crush: Becomes obsessed with defeating Saitama after being curbstomped by him twice. In his own words, he can't overcome the feeling of being a loser unless he beats Saitama. Unfortunately for him...
- Super Speed: Sonic's main ability is his extreme speed. He has been shown to be capable of dodging rocks and trees thrown at him with incredible force. How Sonic obtained his ability is unknown, but so far only Saitama and the monsterized ninjas have been able to keep up with him.
- Time to Unlock More True Potential: You've got to hand it to him, he trains really hard to try and give Saitama a challenge. Not that it helps, mind, but still he goes off to train and get more abilities after almost every defeat. And then when he decides Hard Work Hardly Works and to just eat a Monster Cell? He cooks it first thinking it'd just be common sense, and winds up just having really bad diarrhea instead.
- Unknown Rival: Although he declares himself to be Saitama's rival, the difference in strength is obvious and Saitama even has a difficult time remembering his name (he calls him "Cross of Bones Panic").
- Villain Respect: While Sonic can't stand the fact that he keeps losing to Saitama and trains hard to defeat him, Sonic is one of the few individuals that takes Saitama and his power seriously.
- Vocal Dissonance: Virtually the only way someone can tell his gender without being told is his surprisingly deep voice. Downplayed a bit in the Latin American Spanish dub, since he speaks with a somewhat effeminate tone, except when he's screaming.
- When He Smiles: Not his slasher one. The OVA shows him smiling and it is pretty nice.
- Wild Card: Due to being an assassin for hire and having no status as a member of the Hero Association.
- Worf Had the Flu: His fight with Sea King; he's unarmed, having just broken out of prison, and while even a fully powered Sea King still can't match Sonic in speed, Sonic can't land any blows powerful enough to hurt him. Sonic runs away, and after arming up comes back, but by then Sea King's pissed off Saitama. According to Word of God, if Sonic had a weapon, he would have defeated Sea King in his base form.
- Worthy Opponent: He sees Saitama as this and won't rest until he defeats Saitama. On the flip side, while Saitama doesn't see Speed-o'-sound Sonic as a threat, he keeps letting him go so that Sonic can grow stronger and maybe pose something of a challenge next time. This is even lampshaded in the third special comic chapter "Catch and Smash".
Voiced by: Toshiki Masuda (Japanese), Miguel Ángel Leal (Latin American Spanish)
Bang's only disciple. Quite the braggart. He was "expelled" by his master for his lack of skill at martial arts, only to realize it was for his sake to keep him away from encountering Garou. Unfortunately, he ignored Bang's secret warning and ended up being beaten by his former fellow disciple.
- Butt-Monkey: He is so insignificant that Saitama initially has difficulty remembering who is.
- Curb-Stomp Battle: Charanko is a worse than average martial artist living in a world of monsters and superheroes, leading to him being on the receiving end of these quite often.
- Doomed Moral Victor: Despite everyone telling him (and perhaps Charanko even realizing) that Garou is too dangerous to mess with and that Charanko is too weak to ever match him in a fight he does it anyway to defend his master's honor. Saitama even mentions to a former disciple of Bang's that Charanko was way stronger than the former disciple (who was second only to Garou in the dojo) because Charanko didn't run, and indeed faced Garou head on.
- Honor Before Reason: He attacks Garou head on even after Bang makes it clear that doing so would end in disaster. It doesn't end well.
- Hot-Blooded: When his master is insulted, he immediately and loudly challenges Genos in a duel, despite Genos being a known S-class hero.
- Overly Narrow Superlative: Was originally the lowest ranking member of Bang's dojo, which was also pretty much what saved him from being trashed by Garou, and subsequently became the top ranked disciple by virtue of being the only one left.
- Small Name, Big Ego: He thought he could take Genos and Saitama in a fight. Genos proved him otherwise.
Voiced by: Kenichi Ogata (Japanese), Doug Stone (English), Jaime Vega (Latin American Spanish)
The scientist who saved Genos 4 years ago by turning him into a cyborg.
- Almighty Janitor: Despite being the reason Genos can blast apart mountainsides and why he instantly became an S-Class hero, Doctor Stench is only seen using his skills to provide Genos with repairs and upgrades.
- Early-Bird Cameo: Appeared in episode 4 fixing up Genos and created the arms that Genos used in the sparring match with Saitama.
- Improbable Hairstyle: He has a bowl-cut that looks more like a mushroom cap.
- Nice Guy: Saitama considers him this after hearing how he gave Genos the ability to taste and convert food to bio-fuel so he can still eat despite being mostly mechanical.
- Parental Substitute: He is a father figure to Genos, expressing concern for him. He always reminds him of not being reckless all the time and that they are together in their battle.
- Science Hero: Genos refers to him as the 'Doctor of Justice'.
- Unfortunate Names
Bang's older brother. A martial artist who is also the Master of the Whirlwind Iron Cutting Fist Style.
- Back-to-Back Badasses: When he teams up with his brother, Bang.
- Badass Beard: In contrast with his brother who has a Badass Mustache.
- Bald of Awesome: While his brother Bang still has his hair, Bomb is bald.
- Bare-Fisted Monk: Like his younger brother, he also uses martial arts in fighting.
- Cool Old Guy: He's Bang's older brother and he's willing to close down his dojo to help his brother deal with Garou.
- Fantastic Fighting Style: The "Whirlwind Iron Cutting Fist Style".
- Feeling Their Age: He often complains about being too old to be active anymore when hunting down Garou with Bang.
- Old Master: He's older than his brother, who is 81. Not is much known about Bomb's strength. However, as Bang's older brother and master of the "Whirlwind Iron Cutting Fist", it is safe to say that his strength is on par with the S-Class heroes.
- Razor-Sharp Hand: His Whirlwind Iron Cutting Fist allows him to generate concentric rings of pressurised air that cuts through opponents.
- Supernatural Martial Arts: Much like his brother, he has his own martial arts, the Whirlwind Iron Cutting Fist Style. Despite being even older than Bang, thus style allows him to fight on equal rank with his younger brother.
- Badass Adorable: Despite being a little girl she stands up to Garou and tells him to leave big brother Metal Bat alone, because he promised to take her to her recital. She then slaps her brother so hard that he passes out though he had already been severely beaten.
- Badass Normal: For essentially taking her life in her hands by stepping between Garou and Metal Bat. She had no way of knowing whether Garou would respect her rules, but it was all she had to protect her brother with.
- Big Damn Heroes: Steps in between Garou and her brother during their fight. Though considering how the fight was going it's unclear who she was preventing from getting killed.
- Canon Foreigner: A god-created one - the arc she first appears in is only in the redraw, but the story's still credited to ONE and she had been mentioned in the webcomic long before this.
- Fangirl: She is one of Sweet Mask. She was annoyed that her brother used his S-Class promotion request for an unbreakable bat rather than for his autograph.
- Hair Decorations: A hairclip.
- Morality Pet: Metal Bat's not a bad guy, but he'd be more of a Jerkass if it weren't for her, not to mention more recklessly hot-blooded.
- Nice Girl: Seems quite friendly, if a smidge overbearing.
- No Hero to His Valet: She tends to scold Metal Bat for things like missing her piano recital when his hero work gets in the way. Word of God is that she's not the kind to brag to other schoolkids about her brother being an S-class hero.
- Not in Front of the Kid: Invoked. Metal Bat promised not to fight in front of her, which she uses to break up his fights when she's nearby.
- Tsurime Eyes: And quite justified, given her first appearance sees her standing up to Garou. (It helps that they're similar to her brother's, giving her "delinquent eyes" despite being very girly in appearance otherwise.)
TareoA young child that loves heroes and who Garo occasionally talks to.
- Badass and Child Duo: Occasionally forms with Garo, being the "Child" to Garo's "Badass".
- Big Ol' Unibrow: To add on to his Gonk appearance.
- Fanboy: Of the Hero Association.
- Gonk: He's not exactly cute for a kid, something that Garo lampshades.
- The Load: In chapter 81 and 82, Garo would have had an easier time fighting off the eight heroes that were sent after him had he not been trying to protect Tareo from being collateral damage in the fight, as the eight heroes were unaware that Tareo was hiding close by.
- Morality Pet: He is pretty much there to show that Garo isn't completely a bad person. Garo is even forced to save him sometimes from being collateral damage by the heroes hunting Garou down and from members of the Monster Association.
- Unwitting Instigator of Doom: The hero catalog he carries around has given a lot of intel to Garo on how to track down heroes and finding their weaknesses.
WaganmaThe son of Narinki, an executive of the Hero Association. His kidnapping spurs the S-Class heroes into taking down the Monster Association.
- All Take and No Give: As mentioned in Ungrateful Bastard below.
- Badass and Child Duo: With Child Emperor.
- Meaningful Name/Punny Name: "Waganma" is a play of words of "Wagamama", which means "spoiled".
- Spoiled Brat: Oh yeah. It's even in his name.
- Ungrateful Bastard: Let us count the ways...
- Takes Tareo's only piece of food without thanking him, then declares him 'useless' for not having more.
- Admonishes Child Emperor for not coming to his rescue quickly enough.
- Constantly insults Child Emperor during his fights.
- Intentionally lies to Child Emperor about Tareo being imprisoned as well, thinking of his own safety.
A martial artist and user of the Void Fist. He is said to be a top contender in the Super Fight tournament.
- The Ace: He is considered a legend for winning 4 Super Fight tournaments in a row.
- Ain't Too Proud to Beg: Beaten up by Gouketsu and surrounded by crow monsters in his weakened state, Suiryu doesn't hesitate to put aside his pride and ask Bakuzan, who's been watching all the while and still more or less at full strength, for help. Bakuzan proceeds to eat all the remaining monster cells instead.
- When he's beaten down to the point of only being able to crawl, he tries begging Bakuzan to spare him (though he drew the line at licking his feet) and shortly after cries out for a hero to save him — anyone at all. Thankfully, this time, Saitama comes to rescue him, Sneck, and Max from certain death.
- All Chinese People Know Kung-Fu: He wears a traditional uniform used in Chinese martial arts, with a black and white top sporting long sleeves and has star shaped decor in front.
- Anti-Villain: Despite his Social Darwinist beliefs and a little arrogance, he is not a bad guy and just serves as a Hero Antagonist to Saitama until Gouketsu's arrival.
- Arrogant Kung-Fu Guy: In the traditional sense. But even more so regarding his lifestyle choice.
- Beauty Is Never Tarnished: Somewhat. Bakuzan punches his teeth in and rips off his hair, but otherwise he's not too disfigured.
- Blood Knight: Subverted. He claims he wishes to feel the thrill of a real fight, just like Saitama and Boros, but the moment he's faced with a situation where he might actually lose, he immediately loses all composure and flies into a rage. He outright states he doesn't find losing to be fun, which contrasts Boros, who had the time of his life even though he completely lost.
- Break the Haughty: Starts when he is completely defeated by Gouketsu. His pride is shown to further break down from his former arrogant nature after desperately asking for help from Bakuzan, knowing full well he cannot win with his strength alone. Bakuzan refuses and he is saved by the same heroes he mocked before. And, in the end, he is once again brutally attacked by monster-Bakuzan, leaving him heavily injured and unable to do more than scream for some hero, any hero no matter how weak, to come save him. Luckily, it's Saitama who comes to his rescue.
- Brilliant, but Lazy: By his own admission, he's never trained particularly hard and would sometimes neglect his master's lessons to spend the day picking up girls instead. At the present day, he admitted that he hasn't even bothered practicing his martial arts at all in the past few years and primarily entered the current Super Fight tournament because he was low on cash. Even so, he's easily leaps and bounds ahead of the A-Class heroes and one of the strongest martial artists seen yet solely through his natural talent.
- Canon Immigrant: Was not in the original webcomic version of the Monster Association arc, like most of the other tournament contestants.
- The Casanova: He enjoys hitting on pretty girls in his spare time. He also only decided to fight the transformed monsters if one of the presentation girls at the tournament would go out with him.
- Charles Atlas Superpower: Good lord! He's strong enough to split the tournament ring in two and lift half of it by stomping his foot all from his martial arts.
- Clothing Damage: Saitama's punch (which he stopped just in time) rips off Suiryu's shirt and shows off his Heroic Build.
- Comes Great Responsibility: Inverted. He believes, since he's insanely strong, that he has the right to just relax, have fun, and do anything he wants. Even when the other competitors turned into monsters, he only faced them in exchange for a date with a girl. Likewise, he believes that heroes who fight for such things as a sense of duty or justice to be either corrupt hypocrites or ineffectual weaklings. He rethinks this position after he's left broken in body and spirit by Gouketsu and later, Bakuzan, and he finally understands what it's like to be utterly powerless against an implacable foe with no one to come to your rescue. Combined with seeing Sneck and Lightning Max fearlessly stand up to Gouketsu despite being hopelessly outmatched to give him a chance to escape and later being saved by Saitama after he's left in utter despair at his situation prompts him to resolve to become a hero himself.
- Curb-Stomp Battle: He defeated Lightning Max, and subsequently Sneck, with a single attack. Receives one from Saitama and, later, Gouketsu.
- Disqualification-Induced Victory: The only way he could have won against Saitama, with the latter being disqualified when his disguise was revealed. He didn't like it to say the least.
- Foil: To Saitama: both are very strong and wish to have a real challenge, but while Saitama is bored of his situation, Suiryu is happy and relaxed, claiming he can do whatever he wants (due to his beliefs). It's actually invoked by Suiryu himself, noticing Saitama specializes in punches, so he decides to use kicks.
- Is also one to Genos, both being extremely powerful individuals who were changed by Saitama. Both Suiryu and Genos didn't think much of heroics until they faced an insurmountable obstacle and were saved by Saitama, who showed them both what a true hero is like. Suiryu even asked if he could be Saitama's disciple too but Saitama had already learned his lesson with Genos and refused.
- The Gift: Despite his youth and his decidedly laid back attitude towards his own martial arts (seeing it only as something to impress girls and win tournament money with), his natural raw skill and power would easily qualify him as an S-rank hero. Bakuzan outright admits that, with how strong Suiryu is at present while still having the potential to grow stronger, he'll never be able to match up to him as a human, hence, why he decided to become a monster.
- Hypocrite: He's very fond of mocking and taking others lightly because he's stronger than them, but the moment Saitama does the same to him, he gets pissed off. He also looks down on heroes as being condescending and self-serving while performing deeds in return for favours even though he's guilty of the same thing.
- Jerk with a Heart of Gold: While he's certainly arrogant, condescending, and self-centred, Suiryu's not really a malicious person at heart. He's also genuinely grateful to Lightning Max and Sneck for saving him in his hour of need, admitting to himself that he was wrong about heroes, and later tries to hold back Saitama from going after Gouketsu after saving him from Bakuzan despite being beaten so badly he can't even stand.
- Jerkass Has a Point: His criticisms of heroes may not apply to guys like Mumen Rider or Saitama (on a good day), and he's just as guilty of using his power to do whatever he wants, but he's not wrong that the Hero Association is corrupt and doesn't actually care about protecting people.
- Let's Get Dangerous!: After seeing how strong Saitama really is, he stops using only kicks and fights with all his strength.
- Long-Haired Pretty Boy: He is this, and went out with a lot of girls. Bakuzan "fixes" this by punching most of his teeth out and ripping off his hair.
- Mr. Fanservice: He has many a Shirtless Scene.
- Normal Fish in a Tiny Pond: The source of his pride. He's legitimately strong and would fit into the lower ranks of S-Class perfectly, but he's limited his world view to what he sees in the tournament ring. Fighting only people much weaker than him has blinded him to just how many monsters and heroes out there are stronger than him. He finally understands this once he fights the Dragon-level Gouketsu and realizes that for all his strength, he can't make the monster even blink.
- Oh, Crap!: He's practically drenched in fear-sweat after his shirt is shredded right off his body just from the wind of Saitama's punch. It's very clear that he's never faced an opponent who was actually a threat to him, much less an opponent who outclassed him completely. It happens again when he realizes that he can barely make Gouketsu flinch and he's not taking it seriously.
- Pride Before a Fall: He enters the tournament smug and assured of his invincibility. He then gets his ass kicked several times over, and has his world view, especially his disdain of heroes, utterly broken.
- Rapid-Fire Fisticuffs: Kick version. Then he uses a mix of the two, that obviously has no effect on Saitama.
- The Reason You Suck Speech: Gave this to Sneck, realizing that most heroes do their job not for justice but only for self-satisfaction, pride and ego.
- Slipknot Ponytail: When receiving the punch from Saitama, his ponytail comes off.
- Smug Super: Is very confident in his abilities, is likely as strong as an S-Class hero, and loves taking time out of his day to remind you of this. Learning firsthand he's not at the top of the pecking order via repeated humiliation humbles him a bit.
- The Social Darwinist: He believes strongly in the philosophy of natural selection, where the strong will always prevail no matter what.
- Sore Loser: Despite claiming that he wanted a fun battle against an opponent that he could cut loose against, the moment it becomes clear that Saitama is much stronger than he is, he immediately throws what is essentially a temper tantrum, drops his carefree attitude and tries to administer a brutal No-Holds-Barred Beatdown on him. When Saitama calls him out on this he actually retorts that he doesn't find losing fun.
- Trauma Conga Line: Suiryu entered the tourney expecting to win the prize money, have a good fight or two, and maybe score a date along the way. What he got instead was the worst day of his life. To whit,
- It begins when he fights Saitama. Despite his best efforts, he can't do anything to Saitama, and wins only via technicality, but he brushes it off.
- Gouketsu then enters the picture, and transforms several other fighters into monsters. Suiryu fights them in exchange for a date with a pretty girl, and beats them with moderate difficulty, but gets rewarded by being beaten halfway to death by Gouketsu and his three crow monster henchmen. Suiryu realizes he's outmatched and throws away his pride to ask Bakuzan for help, only to have Bakuzan refuse and transform into a monster instead. He's saved from one killing blow at the last second by Sneck and Lightning Max, who he disparaged for being heroes and weaker than him, only to watch in horror as they sacrifice themselves to buy him time to escape. He tries...
- ... but gets blocked and beaten down even further by the now fully transformed Bakuzan. All he can do at this point is crawl along the ground with tears in his eyes and scream out for a hero, the ones he looked down on so much, to come save him. It's this final moment of humility that causes Saitama, his last tournament opponent, to come to his rescue.
- Villainous BSoD: While it's a bit of a stretch to call him a villain, he didn't take his "loss" against Saitama very well. However, he snapped out of it pretty quickly and decided to just forget about the encounter.
- Willfully Weak: He decides to use only kicks to contrast himself from Saitama but can also fight with punches as well.
- The Worf Effect: He is heavily outmatched by Gouketsu, who is completely unfazed by Suiryu's most powerful attacks.
- Worthy Opponent: Subverted. While he does search for strong opponents and takes some pleasure fighting someone who can actually make him work for a victory, if it actually seems like he's going to lose his playful attitude will immediately do a 180.
A martial artist and user of the Dark Hell Assassination. He is said to be a top contender in the martial arts tournament.
- Arrogant Kung-Fu Guy: He is extremely arrogant during battle since he states that all contestants in the Super Fight Tournament are a bunch of weaklings. Bonus point for being a martial artist. He eats a bunch of monster cells all at once with the intent of becoming the strongest monster alive, even after Gouketsu tells him not to, and all it gets him is his death... until it turns out he did survive and became potentially a Dragon-level threat.
- Berserk Button: Fellow martial artists who treat the tournament as sparring and competition. He becomes irate when Saitama does not take on a stance, believing him to be untrained and an insult to fight.
- Blood Knight: He is quite bloodthirsty, wanting to kill Suiryu. He proves it again when detailing how he will hurt Saitama with a smile on his face.
- The Brute: Bakuzan is a muscular built man with spiky, dark hair. He is excessively brutal towards his opponents, especially those he feels are not worthy of facing him. Up to Eleven after his transformation into a monster.
- The Bully: After becoming a monster, he admits to himself that the only reason why he wanted strength was to pick on those weaker than him. He proves it by torturing a half dead Suiryu.
- Even before his monsterization, he was this, thrashing his opponents so badly that the referee and medics had to be on immediate standby to call the match and get his opponent medical attention because of how quickly he could, and would, inflict potentially-lethal injuries in a tournament fight. Becoming a monster merely makes him willing to admit this outright.
- Curb-Stomp Battle: When Saitama asks for a demonstration of his strength, Bakuzan agrees to comply, detailing exactly how he intends to defeat Saitama, in a brutal, exceedingly cruel fashion. However, he touches Saitama's head and nearly knocks over his wig, causing Saitama to punch him into the air in panic.
- When he transforms into a monster, he doesn't hesitate to land one on Suiryu (weakened after the defeat against Gouketsu).
- He tries to do the same with Saitama but, much to his horror, Saitama is unfazed from all his attacks and blows off half of his body, killing him.
- Driven by Envy: Admits he's always been jealous of Suiryu, which plays a big part in why he chooses to become a monster.
- Foil: To Suiryu and even more so, most heroes. While Suiryu seeks strength to have an easy life and most heroes seek strength to protect the innocent, Bakuzan wants to be strong only because he wants to torment everyone weaker than him.
- Jerk with a Heart of Jerk: After Suiryu asks him for his aid in fighting the monsters, Bakuzan looks like he's gonna consider it and commit to a Rivals Team Up...and then he refuses and chooses to eat a monster cell instead. Once his transformation completes, his first act is to brutally stomp Suiryu.
- Karmic Death: Subverted. Despite Suiryu asking him to help him fight the monsters after he realizes he can't do it alone, Bakuzan refuses and chooses to eat a bunch of monster cells so he can try and become the strongest monster, which seemingly overloads his body and kills him. Instead it turns out he survived and even became a Dragon-level threat in the process.
- Multi-Armed and Dangerous: His monster form has 2 pairs of arms which make his attacks deadlier.
- Sadist: In his monster form he loves torturing his victim physically and mentally. He brutalizes a heavy injured Suiryu by rapidly pummelling him as well as taunting him to the point of making Suiryu feel totally hopeless. His love for torment also goes as far as being willing to stomp Sneck in front of Suiryu in order to show that no heroes will come to save him.
- Unknown Rival: To Suiryu. He's envious of Suiryu and wants to beat him to prove he's the strongest, Suiryu gives him only a glance at best.
- When Saitama fights him as a monster, he keeps trying to remember where he met him before, forgetting he encountered him in the tournament.
Sour Face was once a disciple of Bang, but left after Garou rampaged through the dojo. Sometime afterwards, he created the Sour Face Style Martial Arts and started his own dojo.
- Arrogant Kung-Fu Guy: Subverted, while he certainly thinks of himself as strong, he immediately understands how much weaker he is compared to the other contestants. Further subverted in his unseen fight with Jakumen; not only did he show complete sportsmanship, but he praised Jakumen's efforts after winning the match.
- The Bully: In the past was this to Charanko using him as a training dummy. However, getting beaten up by Garou seems to have mellowed him out and he's now sincerely worried about him when he saw his powerful opponents. Luckily, Charanko was actually Saitama in disguise.
- In a retconned chapter of the redraw, he actually attacked Charanko(Saitama)outside the match. However, this is no longer canon.
- Dumb Muscle: Not really a genius. For example, when Saitama loses his wig, Sourf Face is the only guy who doesn't understand that was a disguise and Saitama is not Charanko.
- Face of a Thug: As cartoonishly ugly as he is, he still has the appearance of a dangerous thug. However, he does show genuine concern for Charanko(Saitama in disguise)'s safety before he faces off against Choze, among other things. See Jerk with a Heart of Gold below.
- Gonk: His most noticeable feature is his taut face, strained to the point where it appears that he has been eating foods that were too sour, and a cleft chin.
- Jerk with a Heart of Gold: Originally bullied Charanko and still acted quite roughly to him in the present (actually Saitama disguised as him) but also showed surprising consideration such as helping him tie his belt properly, defending him when he was being trash talked by Zakos and showing concern at the opponents he would face. Also, in the one match he participated in, he showed great sportsmanship and praised his defeated opponent.
- Performance Anxiety: So much that he's completely paralyzed when the announcer introduces him. Of course, this is before he realizes just how strong the other contestants are.
- Younger Than They Look: He's barely twenty. That pinched, creased face makes him look like he's at LEAST in his late thirties. He's also rather sensitive about it.
A martial artist and user of the Fist Of The Pure Blood Master Race.
- A Nazi by Any Other Name: Seemingly invoked intentionally to draw him no sympathy. He wants his "superior" race to take over the world and he wants to prove that everyone else is worthless. He gets worse when he becomes a monster, deciding that all "inferior" beings must be wiped out and that he will eliminate anyone who doesn't pass his "selection process". He even has an attack that's designed to wipe out "inferior races". He is defeated by Saitama and killed by Suiryu.
- Arrogant Kung-Fu Guy: Choze is an arrogant man that looks down on others. He thinks that his masterpiece genetic material and the careful genetic breeding practices of his clan can make him and his clan superior to other normals and the feeble population of the Earth.
- Curb-Stomp Battle: Defeats his opponents very easily, then gets defeated with one punch by Saitama, who finds him very annoying.
- Empowered Badass Normal: Easily kills Rosie, another participant who became a monster, and eats one of the monster cells to become a monster himself. He is able to have a tough fight with Suiryu.
- Jerkass: During combat, he is quite vicious and bloodthirsty as he often beats his opponent to the verge of death. And he doesn't hesitate to eat a monster cell.
- Ki Attacks: After becoming a monster, Choze is able to use a technique that projects a powerful energy beam from his horns. It is strong enough to cause Suiryu to struggle while holding it back.
- Revenge: As a monster he vows to kill Saitama for humiliating him.
- Sadist: He is shown to be extremely sadistic, to the point where the screams and tears of his opponent are merely "fun" for him.
- Spikes of Villainy: In the monster-form, he grows spikes on his shoulders and his head seems to start to blend in with his attire. His hands become spiked and black.
- Super Breeding Program: He is extremely powerful because his clan chooses only the best genes to transmit.
- Super Strength: After transforming into a monster, his strength increased to the point where one punch is enough to send a contestant of the Super Fight tournament flying out of the stadium.
BenpatsuA martial artist and user of the Harsh Path Style. He and his dojo were the main antagonists of the Lobster special.
- Arrogant Kung-Fu Guy: Benpastu is an arrogant man, looking down on heroes like Sneck.
- Butt-Monkey: He only shows up to get destroyed by everyone in one hit.
- Curb-Stomp Battle: Twice. From Sneck and, as a monster, Suiryu.
- Dirty Coward: He doesn't mind using tricks during fights, such as asking Sneck to stop only to strike him with an attack. He is also cowardly as shown when he runs away in an attempt to save his own life after Mysterious Beings attack the stadium.
- Power Up Letdown: When he becomes a monster, he gets a third eye and sharp teeth. That's it.
- Shout-Out: He is drawn in a comical style very closely resembling that of a pre-Z Dragon Ball villain. The third eye even resembles that of Tenshinhan from the same series.
- Third Eye: As monster, he gains an additional third eye.
- Underestimating Badassery: He assumes that Sneck is weak since he's the lowest ranking hero. Sneck is quick to correct that he is only the lowest ranking hero in A-class. He tries to punch Sneck, only to be counterattacked by Sneck's attack and defeated.
VoltenA martial artist and user of the Thunder Thunder Fist.
- Curb-Stomp Battle: He was defeated by Suiryu during the semi-final in 3 seconds with one single kick. Even after becoming a monster, he was no match for him.
- Lightning Can Do Anything: Volten was struck by lightning as a child, which turned him into a superb fighter.
- Shock and Awe: Volten is described as having a super conductor body. After becoming a monster, his electrical ability seems to have increased drastically.
ZakosA martial artist and user of the Head First Rushing Style.
Lin LinLin Lin (or Ring Ring, depending on the translator) is a martial artist and user of the Palm Bell Fist.
- Anime Chinese Girl: Her look seems to invoke this trope. Resemblances to Chun-Li have been noted by several.
- Faux Action Girl: She is rumored to stand at the top of female martial artists. However, she was beaten by Max without any trouble (although Max disagreed) and was called a lightweight by Zakos. Comparatively, considering how overpowered some characters in One Punch Man are, she'd be an average martial artist of the lot.
- Punny Name: Her name in some translations, Ring Ring, is directly tied to the bells she wears and uses for combat.
- Ship Tease: With Max.