One-Punch Man features an array of incredibly powerful villains, each designed to test the limits of its invincible hero. Despite Saitama’s unmatched strength, these villains often get to showcase their destructive abilities before encountering him.
Many of them have overpowered lower-ranked heroes and wreaked havoc on cities, displaying just how formidable they are.
Even the strongest enemies crumble when Saitama finally steps in (Photo: One Punch Man/Madhouse)Even though Saitama remains undefeated, some adversaries have pushed him further than others. Given the nature of the series, creator ONE has introduced villains with unique abilities that make every battle more intense.
The most fearsome enemies in One-Punch Man highlight just how extreme the action in the series can be.
15. Bakuzan Became a Greater Threat After Transforming
Participating in the Super Fight tournament, Bakuzan was already an exceptional martial artist before undergoing a monstrous transformation. After accepting an offer from Goketsu to become a monster, his abilities became even deadlier.
The moment he gained this newfound power, he immediately set his sights on Suiryu, one of the few competitors who refused the transformation. However, Bakuzan’s reign was short-lived, as Saitama arrived and obliterated half his body with a single attack, just as he did to the other fighters who consumed monster cells.
14. Centichoro’s Gigantic Form Made It a Nightmare Opponent
A massive centipede monster emerged at the end of One-Punch Man’s second season, proving to be an overwhelming threat. Its sheer size alone was enough to level cities, and it relentlessly engaged Genos, Bang, and Bomb.
Even Genos, using his maximum firepower, only managed to force Centichoro to molt, making its armor even tougher. Before things escalated further, Saitama intervened and unleashed a devastating punch, causing shockwaves that completely destroyed the creature from within.
13. Homeless Emperor Gained Immense Power from a Mysterious Entity
Unlike many other monsters, Homeless Emperor was once an ordinary man, but everything changed when an enigmatic entity known as God granted him incredible energy-based abilities. This newfound power enabled him to unleash massive attacks, striking multiple opponents at once.
Driven by a warped sense of purpose, he believed he was chosen to punish humanity for the suffering he had endured. In an ironic twist, Homeless Emperor never fell at the hands of a hero—he was eliminated by God himself, who sought to keep his secrets hidden.
12. Gums Had a Deadly Appetite That Left No Survivors
Serving as a high-ranking member of the Monster Association, Gums was a grotesque creature whose body was little more than a massive, insatiable mouth. He had the horrifying ability to consume his victims whole, rapidly dissolving them with the powerful acids in his stomach.
Although he lacked intelligence, his sheer hunger made him a lethal adversary. His downfall came when he mistakenly ingested another monster, Fuhrer Ugly, who managed to tear through his body from the inside, killing him.
11. Carnage Kabuto Knew Saitama Was a Serious Threat
One of the most dangerous creations from the House of Evolution, Carnage Kabuto possessed an imposing beetle-like form that hinted at his immense strength. He easily deflected Genos’ attacks with nothing more than his breath, proving himself to be far stronger than many expected.
Unlike most opponents, he instinctively recognized Saitama’s power before the fight even began. Despite his intimidating nature, he was swiftly defeated once Saitama realized their battle was cutting into his time for grocery shopping.
10. Deep Sea King Wiped Out Multiple A-Class Heroes Effortlessly
An early yet terrifying foe, the Deep Sea King established himself as a dangerous force, effortlessly overpowering numerous A-Class heroes. Even the formidable S-Class hero Puri-Puri Prisoner couldn’t stand against him.
His ruthless nature was evident when he attacked a shelter filled with civilians, intending to massacre everyone inside.
Bakuzan’s monstrous transformation only delayed the inevitable (Photo: One Punch Man/Madhouse)His strength increased exponentially when exposed to heavy rain, nearly destroying Genos in the process. While Saitama easily finished him off, he downplayed his role to protect the reputation of the other heroes, earning respect from those who witnessed the battle.
9. Goketsu’s Power Transcended His Martial Arts Skills
As the primary antagonist of the Super Fight arc, Goketsu stood at the top of the Monster Association’s ranks. He sought to transform elite fighters into monsters, believing that power was all that mattered.
Once a human martial artist himself, he willingly embraced becoming a monster to achieve even greater strength. Saitama’s intervention prevented his plan from succeeding, as he swiftly decapitated Goketsu with minimal effort.
8. Fuhrer Ugly Had a Deep Hatred for Beauty and Showed No Mercy
A cruel and sadistic monster, Fuhrer Ugly harbored an intense resentment toward those he considered attractive. He effortlessly dismantled Sweet Mask, the highest-ranked A-Class hero, and became even more formidable after surviving partial digestion by Gums.
This incident granted him acid-based abilities, which he used to burn the skin of S-Class hero Blackluster. Despite his destructive capabilities, Garou brought an end to him, delivering a devastating blow that tore through his chest.
7. Boros Proved to Be a Rare Opponent Who Could Keep Up with Saitama
Leading the Dark Matter Thieves, Boros traveled across the galaxy in search of worthy challengers. Unlike most adversaries, he was not only incredibly strong but also possessed regeneration abilities and energy attacks that made him especially dangerous.
His armor, initially mistaken for protection, was actually a limiter suppressing his full strength. He came closer than anyone to making Saitama exert effort, even sending him to the Moon with a single strike. However, it still wasn’t enough, as Saitama’s “Serious Punch” ended the battle definitively.
6. Psykos’ Psychic Abilities Made Her a Terrifying Opponent
A former human who sided with the monsters, Psykos possessed immense psychic powers that were further amplified after her transformation. Her past connected her to the Psychic Sisters, Tatsumaki and Fubuki, as she had once been a classmate of Fubuki.
Seeking even more strength, she attempted to merge with Orochi, the King of Monsters. However, Tatsumaki proved to be too much for her, using her own psychokinetic power to bring Psykos down.
5. Platinum Sperm Merged into a Nearly Unstoppable Being
Starting as a swarm of creatures known as Black Sperm, Platinum Sperm was the result of countless individual bodies combining into one. His combat speed was astonishing, allowing him to exchange thousands of blows in milliseconds during a three-way battle with Garou and Flashy Flash.
While he was one of the strongest monsters to emerge, Garou’s ever-evolving abilities soon outmatched him, bringing an end to his reign.
4. Evil Natural Water Weaponized the Power of the Ocean
Among the strangest monsters in the series, Evil Natural Water was a sentient liquid that grew stronger by merging with larger bodies of water. When it expanded into Evil Ocean Water, it unleashed high-pressure water beams and created massive waves.
No matter how terrifying the enemy, Saitama ends every battle instantly (Photo: One Punch Man/Madhouse)It could drown its enemies with ease, making it a lethal opponent. Saitama ended its destruction by delivering a “Serious Punch” that parted the sea itself.
3. Centisennin’s Size Rivaled Even the Largest Monsters
Another centipede-based monster, Centisennin towered so high that its head nearly reached the atmosphere. It emerged from underground, having previously battled Blast, the top-ranked S-Class hero.
Unlike previous centipede monsters, it saw Saitama as an unparalleled menace, referring to him as “The Abominable Fist That Turned Against God.” However, Garou was the one who took it down with a single powerful strike.
2. Orochi’s Monstrous Strength and Adaptability Made Him Lethal
As the leader of the Monster Association, Orochi wielded terrifying power, with abilities that allowed him to morph his body and absorb energy from the Earth’s core. Initially defeated by Saitama, he later fused with Psykos, gaining gravitational control and the ability to assimilate other entities.
Tatsumaki ended the battle, proving her dominance over the monstrous fusion.
1. Garou Pushed Saitama Further Than Any Other Villain
Garou’s transformation into a cosmic-level threat marked the peak of One-Punch Man’s villain roster. Constantly evolving, he reached a form where he wielded the destructive power of the ultimate entity, God. Their fight destroyed on a planetary scale, even reducing a section of Jupiter.
His defeat came when Saitama reversed time with an attack, erasing the battle’s consequences and leaving a version of Garou from before his transformation intact. His role as Saitama’s greatest adversary remains unmatched.