Vaccine Man is a Mysterious Being and the first opponent Saitama faces in the series, introduced in the manga's opening chapter as a Dragon-level threat. He claims to have been born from humanity's own pollution and industrial waste — a self-styled incarnation of nature's wrath, tasked with wiping out humanity to "vaccinate" the Earth against future harm.
He stands roughly two meters tall in his base form, with two antennae on his forehead and veins running across his entire body; when angered he can grow to a towering 18 meters. None of it matters against Saitama, who ends the fight in a single punch — the first demonstration of the one-hit pattern that defines the rest of the series.
In his base form, a tall, muscular, dark-skinned humanoid with two long antennae tipped with bulbs, pointed ears, and no clothing. Enraged, he transforms into a colossal, spiked, jagged-toothed monster with entirely white eyes.
Misanthropic and messianic — he views humanity as a “disease” and himself as the Earth’s cure, a self-righteous mindset that leaves no room for doubt. Short-tempered, especially when that mission is met with indifference.
Claims to have been born directly from the “Will of the Earth” as a response to humanity’s environmental destruction. Nothing else about his origin is stated; he simply appears in City A to begin his campaign.
Vaccine Man devastates City A with energy blasts, then delivers a lengthy manifesto to Saitama about “vaccinating” the Earth against humanity. Enraged by Saitama’s casual indifference, he transforms into his monstrous form — and is killed by a single punch before he can land a blow. The Hero Association later mistakenly credits S-Class hero King with the kill, since King happened to be at the scene.
Fires large destructive energy spheres capable of leveling skyscrapers, can fly, and can transform to increase his size and power. None of it mattered against Saitama — he had no way to sense or survive a single punch.
vs. City A — Ch. 1
Launched a surprise assault that leveled a chunk of the city and likely killed thousands.
vs. Saitama — Ch. 1
Delivered his manifesto, transformed into his final state, and was gone in a single punch — Saitama's first on-screen kill in the series.
Major: Ch. 1. Minor: Ch. 2 (shown as remains). Mentioned only: Ch. 18, 38, 142.
Saitama: his killer, whom he considered an insignificant, “boring” human right up to the end. King: wrongly credited by the public and the Hero Association as the one who defeated him.
“I exist because of humankind’s constant pollution of the environment! I am Vaccine Man!”
“The Earth is a single living organism! And you humans are the disease-causing germs killing it!”
Often cited as an homage to Piccolo (Dragon Ball) and Baikinman (Anpanman). His attack on City A stood as one of the most devastating single-monster events in the series until the later Alien Invasion arc.
🇯🇵 Japanese Voice Actors
Nakao, Ryusei
🇯🇵 Japanese
🇺🇸 English Voice Actors
Sabat, Christopher
🇺🇸 English