The Superheroes of Earth are a collection of individuals with special powers who fight to protect the people of Earth. They appeared to battle The Perfect One. It's not clear whether they originate in the PCG Universe, or from another.
Many of these heroes are DC Universe characters, while others are from Marvel.
Superman[]
Main Article: Superman
Superman is a Kryptonian superhero, with incredible powers. However, even he wasn't able to defeat the Perfect One, as that being was able to synthesize Kryptonite -- Superman's weakness -- to attack him with. (The Perfect One: "T.P.O vs. Superheroes of Earth")
Krypto[]
Krypto is Superman's pet dog, who has all the same powers and abilities. His signature move is his super-urine, which ultimately proved ineffective against T.P.O. (The Perfect One: "T.P.O vs. Superheroes of Earth")
The version of Krypto seen in the Perfect One comics is the same one from the author's series of Krypto fan comics, which feature him using super-urine to put out fires and such.
Batman[]
Main Article: Batman
Batman is a vigilante who uses martial arts and gadgets. Even these were unable to stop the rampaging Fat Guy, however. (The Perfect One: "T.P.O vs. Superheroes of Earth")
It's unclear if Batman is the same as Earth Scientist B. Wayne, a character who has appeared in previous issues of The Perfect One, and who is clearly based on Batman.
Green Lantern[]
Green Lantern is a superhero who uses a ring that projects energy force fields. These can be used as a powerful laser-like weapon, or to form constructs to attack with. Unfortunately, he was overcome in the battle with T.P.O. as well. (The Perfect One: "T.P.O vs. Superheroes of Earth")
Adam wished for a Green Lantern ring at the beginning of time, and thus would have become a Green Lantern himself, if only he had thought to wish for the battery as well. (Soul Symphony: "Genesis")
Wonder Woman[]
Wonder Woman was an Amazon superhero, with incredible powers. She was summoned along with the Justice League, and was promptly defeated by T.P.O. (The Perfect One: "T.P.O vs. Superheroes of Earth")
The Flash[]
The Flash is a superhero able to run at incredible speeds. Sadly, he wasn't fast enough to stop T.P.O. (The Perfect One: "T.P.O vs. Superheroes of Earth")
Justice League[]
The Justice League was a team of super-heroes. It's not known who its members are. (The Perfect One: "T.P.O vs. Superheroes of Earth")
The author didn't realize that the above mentioned heroes typically make up the Justice League, and so he had the League summoned to fight TPO after those heroes' defeat -- making it unclear who belongs to the League.
The Hulk[]
The Hulk was a super-hero who becomes a massive, hulking thing when angry. While the Fat Guy must have made him very angry, as he does everyone, he apparently wasn't angry enough. (The Perfect One: "T.P.O vs. Superheroes of Earth")
Ginkus[]
Main Article: Ginkus
Ginkus appeared as one of the Superheroes of Earth, battling T.P.O. He was the last one to join the fight, after the others had mostly been defeated. He unleashed incredible amounts of energy against TPO, and for a time seemed to be having an effect. But soon he, too, was defeated. (The Perfect One: "T.P.O vs. Superheroes of Earth")