Hammerhead (ハンマーヘッド Hanmāheddo) is a B-Class Criminal and former leader of the Paradisers, a now-defunct terrorist group that espoused the idea that people shouldn't have to work if they don't want to.
Hammerhead is a tall, muscular man with piercing eyes and a horizontal scar across his nose. Like the rest of Paradisers, he is completely bald and wears a black, full-body battle suit, although his rank is indicated by unique flame decals emblazoned across its torso and thighs.
As head of the Paradisers, Hammerhead strives to create a utopia in which work is voluntary, and the unemployed receive full financial support. Despite his leadership role, he lacks the charisma to rally any support for their misguided cause, and resorts to terrorism to garner attention.
Paradise Group ArcEdit
After several futile appeals for revolution towards passerby in F-City, Hammerhead leads his Paradisers, outfitted in stolen high-tech battle suits, on a mission to demolish the mansion of Zeniru, which he views as a symbol of social inequality.  After they destroy the wrong building, they easily defeat the riot police and Mumen Rider, but are intercepted by Zeniru's bodyguard, Speed-o'-Sound Sonic, in the woods around Zeniru's mansion.
Hammerhead rejects Sonic's call for surrender and attacks him, only to see his entire Paradise Group massacred, and narrowly avoids death himself. Despite leveraging his suit's immense strength against Sonic and using clever strategy, he is stabbed in the back of his head with a kunai and presumed dead. 
Thanks to his thick skull, he survives and flees the scene, only to encounter Saitama, incensed at being typecast as a member of the Paradise Group. After receiving a blow to the face from Hammerhead's suit, Saitama expresses disappointment at its pitiful strength, prompting Hammerhead to trigger the battle suit's full power. Saitama remains unimpressed, but feels a trace of empathy for Hammerhead, and merely destroys his suit rather than kill him.
Hammerhead is left naked and allowed to escape, but is found, beaten, and left for dead by robotic assassins from a mysterious group known as The Organization, surviving again due to his thick cranium. Lying in his own blood, he cries streams of tears, thanking his mother for giving him his thick skull. He then vows to give up his cause and look for a job.
Hero Association SagaEdit
Rumored Monster ArcEdit
During an investigative briefing at the Hero Association HQ, A-Class Superhero Sneck reports sightings of Hammerhead outside of a job center in F-City, wearing a formal suit and nervously preparing for a business interview.
Alien Conquerors Arc Edit
Abilities and PowersEdit
As a B-Class criminal, it can be assumed that Hammerhead is a reasonable threat, being able to match B-Class heroes in terms of power.
Enhanced Strength: Even without his battle suit, Hammerhead possesses a great amount of physical strength, being able to hospitalize twenty people.
Thick Skull (超頭骸骨, Chō atama gaikotsu): As his name suggests, Hammerhead possesses a cranium several times thicker than a normal human's and dense enough to withstand bladed and blunt trauma. On multiple occasions, this has allowed him to survive attacks that would normally kill a person.
Enhanced Senses: Hammerhead appears to have senses above average level. This is seen when he was able to sense something wrong while on his way to Zeniru's place, which was Sonic hiding in the shadows.
Expert Hand-to-Hand Combatant: Hammerhead has a history of street brawling, having once put twenty people in the hospital. Despite his plain appearance, he employs some amount of strategy in combat, using his environment to set up crude choke points for his opponent.
- Spin Attack (グルグルアタック, Guruguru Atakku): Hammerhead rapidly swings his arms back and forth.
Battle Suit (Formerly): Hammerhead's battle suit protects him from all manner of attack and enhances his strength to superhuman levels, enough to create ground-splitting shock waves and lift massive objects with ease. The suit was destroyed by a single hit from Saitama.
- Full Power (フルパワー, Furupawā): Under duress, Hammerhead can further augment the suit's power to gain even more size and strength, though its extent is not shown.
- ↑ 1.0 1.1 1.2 One-Punch Man Encyclopedia; One-Punch Man: Hero Perfection, page 124-125
- ↑ 2.0 2.1 One-Punch Man Manga; Chapter 12, page 5
- ↑ 3.0 3.1 One-Punch Man Manga; Chapter 14, page 12
- ↑ One-Punch Man Manga; Chapter 12, page 10
- ↑ One-Punch Man Manga; Chapter 13, page 7
- ↑ One-Punch Man Manga; Chapter 13, page 24
- ↑ One-Punch Man Manga; Chapter 14, page 8
- ↑ One-Punch Man Manga; Chapter 14, page 23
- ↑ One-Punch Man Manga; Chapter 20, page 11
- ↑ One-Punch Man Anime; Episode 11
- ↑ One-Punch Man Manga; Chapter 13, page 16
|S-Class||Garou • Speed-o'-Sound Sonic|
|A-Class||Big Iron • Bull-Bull • Serial Bomber|
|C-Class||Banero • Don Pacino • Pacino Family|
|Ex-Villains||Dr. Genus • Hammerhead • Men's Esthetician Man|
|Undetermined Class||Aburabozu • Base B • Burigura • Chimagusa • Coalition of Assassins • Cow's Stomach • Demolition John • Devil Storm • Fukegao • Harold • Paradisers • Smelly Lid Old Man • Special Moves Mile|