Vaccine Man

Vaccine Man (ワクチンマン, Wakuchin Man) was a Mysterious Being supposedly born from the release of excessive pollution and waste generated by the industries made by human beings. According to him, he was created as an incarnation of nature's wrath who is tasked to wipe out humanity and thus effectively "vaccinate" the earth against future "infections."

Appearance
Vaccine Man is a large, hairless humanoid with two rounded antennae on his head. He has a bare muscular body, but Vaccine Man has demonstrated he is capable of shapeshifting, once transforming into a more complex form armed with large claws and fangs.

Personality
Acting as the anti-hero antagonist, Vaccine Man set out to extinguish humanity for the sake of his interpretation on the status of the environment being poor, as humans are considered to him to be an "infection" that withers the environment to a polluted, tainted mess of machinery and carcasses of organisms. The thought of opposition enrages him for he believes he acts out the wishes of planet Earth.

History
Vaccine Man was created as a response to the industrial reign over nature. Conceived by nature, in his own words, he has been formed to serve as the apostle of mother Earth and under the wishes of such. He believes the Earth as a single living organism that is in need of protection and relief of pain, so Vaccine Man has set out to carry out the deed in extinguishing humanity so nature can prosper completely once more. To do this, he has tasked himself to attack the areas where humans are known to live in an infrastructure of technology and artificial order.

Introduction Saga
Vaccine Man appears next to A-City, creating a crater as a result of his travels. He conceives multiple balls of energy that cause further destruction to A. Lightning Max and Smile Man were sent after Vaccine Man but are defeated easily. He then notices a crying schoolgirl and proceeds to grab and crush her. She is saved at the by Saitama, who Vaccine Man questions regarding the hero's identity. Saitama responds he is just an average hero doing average hero things as a hobby.

Offended at Saitama's casual attitude, Vaccine Man launches into a diatribe about his name and purpose while transforming into his second form. Saitama quickly defeats him in a single punch, the staple of the latter's heroic deeds for the rest of the series. Credit for defeating him ultimately went to King.

Abilities and Powers
Vaccine Man is a creature of great strength, enough so to be classed a threat level of "Dragon." He can destroy a large part of a big city and defeat 2 A-Class heroes by himself on the same day, though Saitama quickly defeated him.

Supernatural Abilities
Energy Balls (エネルギー弾, Enerugī-dan): He can shoot energy balls which cause large-scale explosions upon cities.

Flight (飛行能力, Hikō nōryoku): Vaccine Man's supernatural powers also have the extent of flight. He is surrounded by an aura that's similar to his energy balls and takes off several feet in the air.

Physical Abilities
Transformation (変身, Henshin): Vaccine Man is shown to morph his hand into a larger spiky form when he was about to crush the schoolgirl. Vaccine Man is also shown to transform into a more advanced form bearing claws, teeth, and visible scales. The extent of this form's power is unknown, as Vaccine Man was killed by Saitama after adopting it.

Quotes

 * (To Saitama): "What kind of ridiculous backstory is that?! 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! The will of the Earth gave birth to me so that I may destroy humanity and their insidious civilization! But you do this for fun?! That's the reason you dare to oppose me, the Earth's apostle!? Then indeed I must wipe humankind from existence!

Trivia

 * Vaccine Man's normal form bears a strong resemblance to the character Piccolo from the popular manga series Dragon Ball. Coincidentally, the character happened to share the same voice actor, Christopher Sabat.
 * His Japanese voice actor is Ryusei Nakao, who also voiced Frieza in Dragon Ball Z.
 * Much like Demon King Piccolo from original Dragon Ball was born out of humanity's evil influence, Vaccine Man was born out of humanity's pollution.
 * Vaccine Man happens to be a parody of the character Baikinman, the primary antagonist of Anpanman. Given that One Punch Man is a reference to Anpanman, Vaccine Man shares the same Japanese voice actor as Baikinman, Ryusei Nakao.
 * Murata stated that the energy balls he uses are the same as Choze and Homeless Emperor.