Ancient King

Ancient King is the monarch of a once-dominant race of dinosaur beings that previously ruled the Earth.

Although their civilization declined, he and his kind still secretly aspire to seize control of the planet again.

His exact Disaster Level is unknown and never formally stated.

In the anime, he appears in Episode 10, titled "Unparalleled Peril," as one of several would-be rulers of Earth, alongside the likes of Ground Dragon, Chitei Ou (Earth King), Shinkaiou (Deep Sea King), and Sky King.

Ancient King has an enormous body resembling a Tyrannosaurus rex.

Despite his beastly appearance, he possesses intelligence comparable to that of a human, making him a true "giant monster with brains."

His skin is so durable that missile attacks do not visibly harm him.

In addition to his physical toughness, he can fire destructive energy beams from his mouth, giving him long-range offensive capability.

At the time of his appearance, he begins to awaken and act in earnest after other aspiring rulers—Chitei Ou and Shinkaiou—have been defeated by Saitama.

Seeing those other "kings" fall, Ancient King emerges from a glacier, apparently ready to become the next contender for Earth’s throne, even before Sky King can take that role.

However, the Hero Association quickly detects his movements and responds.

They dispatch Terrible Tornado, who uses her psychic powers to pull down a meteorite from space and smash it directly into Ancient King, killing him instantly.

Despite his impressive build-up and implied power, Ancient King is effectively one-shot in spectacular fashion by Terrible Tornado.

This abrupt defeat underlines just how overwhelming her psychic abilities are, especially compared to most monsters.

Although he is primarily an anime-original monster, a similar dinosaur-like creature is said to briefly appear in the original webcomic.

There is also a mention that a colossal monster shown in a single panel in Chapter 67 of the manga bears a strong resemblance to him, though it is unclear if this is intentional design continuity or a coincidence.

Ancient King’s voice actor in the anime is Hiroki Goto.

He has no known civilian identity, background story beyond being the ruler of the dinosaur race, or detailed personal profile such as age or origin point.

Ancient King has a colossal dinosaur-like body reminiscent of a Tyrannosaurus rex.

His sheer size gives him tremendous physical presence and suggests immense physical strength, even though he never gets to showcase it fully in battle.

He possesses a highly developed intellect on par with humans.

This intelligence implies that he can strategize and command, setting him apart from mindless kaiju-type monsters.

His skin is so tough that modern missiles have effectively no impact on him.

This extreme durability hints that, in a normal fight, conventional Earth weaponry would be nearly useless against him.

Ancient King can fire powerful destructive beams from his mouth.

These energy attacks serve as his primary offensive weapon, making him dangerous both up close and at range.

Despite these formidable traits, his actual on-screen combat is extremely brief due to Terrible Tornado’s intervention.

The meteor strike that kills him happens so quickly that he has no chance to show the full extent of his power or tactics.

Ancient King appears during a period when multiple powerful monsters are attempting to claim control over Earth.

Chitei Ou and Shinkaiou have already been defeated by Saitama, and Sky King is also on the board as another self-proclaimed ruler.

Sensing a power vacuum, Ancient King awakens from within a massive glacier.

He begins to move with the clear intention of launching a serious campaign to reclaim Earth for his dinosaur race.

The Hero Association detects his movement and assesses the threat.

Recognizing his potential danger, they request assistance from Terrible Tornado, one of the strongest heroes alive.

Terrible Tornado confronts the situation with her overwhelming psychokinesis.

Instead of engaging him in a prolonged battle, she telekinetically summons a meteorite from space and slams it into Ancient King.

The impact annihilates Ancient King instantly, leaving no opportunity for a prolonged fight.

This one-sided defeat demonstrates just how massive the power gap is between him and top-tier heroes like Terrible Tornado.

Narratively, Ancient King functions as a flashy but short-lived demonstration of escalating monster threats.

At the same time, his instant defeat keeps the spotlight on the S-Class heroes’ absurd power levels rather than on a drawn-out villain arc.

Ancient King is categorized as an anime-original monster for the One-Punch Man television series.

He does not have a fully fleshed-out arc in the original webcomic or manga, though similar designs appear briefly.

A monstrous dinosaur-like creature that resembles Ancient King appears in a single panel of Chapter 67 of the manga.

While it is not confirmed that this is explicitly the same character, the visual similarity suggests he may have inspired or been inspired by that design.

His overall look combines classic giant-monster aesthetics with a more intelligent expression and posture.

This reinforces the idea that he is not just a rampaging beast but a calculating ruler of an ancient race.

Ancient King is voiced by Hiroki Goto in the anime adaptation.

The performance emphasizes his imposing, regal tone, even though his screen time is short.

Ancient King is part of a loose thematic group of "kings" who aim to rule or reclaim Earth.

These include:

Chitei Ou (Earth King) – Ruler of an underground civilization defeated by Saitama.

Shinkaiou (Deep Sea King) – Ruler of the deep-sea people, also defeated by Saitama.

Sky King – A ruler of sky-dwelling creatures who seeks dominion over the surface world.

Opposing these would-be rulers are heroes and organizations such as:

Saitama – The titular One-Punch Man, who defeats multiple "kings" with overwhelming ease.

Terrible Tornado – The psychic powerhouse who annihilates Ancient King with a meteor.

Hero Association – The organization that detects threats like Ancient King and dispatches heroes.

Ancient King’s quick demise means he never directly interacts with Saitama on-screen.

However, his awakening is clearly triggered in a world already shaken by Saitama’s effortless victories over other high-profile monsters.