Out of all the characters in One-Punch Man, Saitama stands at the pinnacle as the strongest being. To date, he has yet to find a villain, hero, alien, or monster capable of fighting him as an equal. However, Saitama aside, there are plenty of other powerful heroes and villains in One-Punch Man. On the one (punch) hand, there are some characters who are considered strong, but whose abilities and full strength remains unknown, such as the top hero Blast. However, there are several characters who have confirmed just how strong they can be. Here is a list featuring the 5 strongest Heroes and Villains in One-Punch Man!
10 Villain: Speed-o’-Sound Sonic
Out of all the villains in One-Punch Man, Speed-o’-Sound Sonic is one of the highest ranked in terms of speed. He also takes great joy when facing opponents stronger than him, which in his case is usually Saitama. Since his first defeat against Saitama, Sonic underwent intense training in order to one day surpass him. In addition to his speed, Sonic also relies on an arsenal of shinobi tools to fight. ONE, the series manga artist, confirms that when wielding a weapon, Sonic is strong enough to defeat Deep Sea King while in his dehydrated form. This also confirms that Sonic’s overall strength is definitely S-Class level.
9 Hero: Genos
When it comes to power, popularity, and amazing fight scenes, Genos is one of the best heroes in the series. Thanks to his cyborg body, Genos is extremely durable and can upgrade his body to become even stronger. After integrating parts from the G4 battle robot, Genos’ speed and power have also undergone a major increase. Genos’ abilities include the power to fire powerful heat beams from his arms, enhanced strength, the ability to move at the speed of sound, as well as limited flight capabilities. Genos also has prior experience in fighting evil organizations and villains, which contributed to his instant promotion to S-Class. He is currently ranked as the 14th top hero.
8 Villain: Carnage Kabuto
As the strongest fighter in the House of Evolution, Carnage Kabuto was so powerful that even his creator could not control him. Although he is as intelligent as he is strong, Carnage Kabuto is mentally unstable and seeks only to destroy. He also has a “Carnage Mode” in which he goes on a week-long rampage and is practically unstoppable. According to the Virtual Genocide System Genos uses to train, Carnage Kabuto is far stronger than him. Even when factoring in his G4 upgrades, Genos was still defeated in all 55 scenarios he’s challenged him. Furthermore, in all these scenarios, Carnage Kabuto does not even use his Carnage Mode.
7 Hero: Metal Knight
Basically the One Punch Man version of Iron Man, Metal Knight, aka Dr. Bofoi, is one of the most powerful and influential members of the Hero Association. As the sixth top-ranked hero, Metal Knight uses a variety of powerful robots to fight on is behalf and has the most firepower among the S-Class heroes. He is so powerful that even the Hero Association lists him as a potential threat if he ever turned rogue. He is also in possession of the spaceship belonging to the alien conqueror Boros. In other words, it is possible that Metal Knight's power may evolve to even greater heights.
6 Villain: Orochi
Orochi is the Monster King and leader of the Monster’s Association. Originally a human martial artist, Orochi was turned into a monster by the telepathic creature Gyoro Gyoro. With multiple serpent-like dragons serving as his “muscles”, Orochi can either modify his body into a mass of large dragons or condense himself into a humanoid form. Orochi can also produce powerful flames for both offensive and defensive purposes. This villain is also highly intelligent and is capable of instantly mastering his opponent's moves, much like he did with Garou’s fighting style. He is also one of the few villains smart enough to deduce Saitama’s true strength.
5 Hero: Superalloy Darkshine
Superalloy Darkshine is one of the most formidable heroes in the series. Compared to the other S-Class heroes, Darkshine is easily the strongest in terms of pure physical strength and durability. Thanks to his buff body, Darkshine’s is highly durable to the point where he can resist attacks from demon-level threats without taking any damage. In some cases, his body can even repel certain physical attacks. He is also fast and strong enough to take on Dragon-level threats like Carnage Kabuto, and he can easily defeat Deep Sea King without exerting any effort. Much like Saitama, Darkshine obtained his current abilities by undergoing intense training.
4 Villain: Garou
Garou is the former top student of the S-Class hero Silver Fang who excommunicated him after he brutally injured his fellow disciples. Garou’s habit of hunting down heroes, including members of the S-Class, has earned him the moniker “Hero Hunter”. Including his martial arts skills, Garou also has a healing factor and has an accelerated growth rate. By fighting strong opponents, Garou’s body adapts and evolves to the point where he becomes a human-monster hybrid. At his max potential, Garou’s overall strength has been compared to the likes of Boros. Although ONE claims that in terms of close quarters combat, Garou is the superior fighter.
3 Hero: Bang
Despite his old age, Bang, aka Silver fang, is more than worthy of his rank as one of the top three heroes. As the founder of the Water Stream Rock Smashing Fist, Bang is one of the strongest martial artists in the world. He is one of the few heroes capable of defeating Dragon-level threats without having to break a sweat and has displayed immense physical strength, durability, endurance, speed, and precision surpassing that of other S-Class heroes like Atomic Samurai and Metal Bat. He is also one of the few heroes able to match an awakened Garou in a battle of physical strength.
2 Villain: Boros
Lord Boros is the leader of the Dark Matter Thieves and is arguably the series’ strongest villain to date. Much like Saitama, Boros suffers an existential crisis after realizing that he has become too strong. Boros is credited with being the strongest opponent Saitama has ever fought. Not only was he able to survive multiple punches from Saitama, but he was also strong enough to kick him to the moon and even put his body back together after Saitama literally punched him to pieces. When drawing on his full strength, Boros can fire laser beams with enough power to decimate a planet.
1 Hero: Tatsumaki
If Saitama is the strongest hero in terms of physical strength, then Tatsumaki is easily his equal when it comes to mental strength. As a result of her powerful esper abilities, Tatsumaki was able to earn her place as the official second strongest hero. When using her psychic powers, Tatsumaki can create psychic barriers, fly at superhuman speeds, instantly stop several large, high-speed projectiles and return them with greater force, suppress the powers of other espers, as well as lift entire cities out of the ground. In the anime, Tatsumaki showed enough proficiency and reach with her powers to summon a giant meteor from space.