The Beyonder was the sum total of a pocket dimension which was accidentally accessed by nebbish scientist Owen Reece. Part of the energy from the dimension escaped and imbued Reece with near-infinite powers which he wielded as the villainous Molecule Man. The remaining energy of the pocket dimension apparently gained sentience and curiosity. Using its vast powers the Beyonder created a planet and abducted a number of superheroes and supervillains so that he could observe the never-ending battle between good and evil that rages within humanity writ large. This was the entirety of the so-called "plot" of the first Secret Wars limited series (12 issues written by Shooter and illustrated by Mike Zeck and John Beatty) published in 1984. The series sold incredibly well with circulation reaching up to 750, 000 copies per issue, numbers reminiscent of the height of comicbook sales during the Golden Age of the 1940s.
Due to the popularity of the first series and Shooter's considerable clout as the editor-in-chief of the entire Marvel comics line at the time, a second Secret Wars series was produced. Imaginatively titled Secret Wars II it was once again written by Shooter illustrated by penciller Al Milgrom and inker Steve Leialoha. Intrigued by what he had witnessed during the first Secret Wars the Beyonder came to Earth to walk among humans and study them and learn of this thing that we call "desire" firsthand. During the course of this belabored 9 issue series the Beyonder encountered and crossed over into the titles of every Marvel comic that was being published at the time. The Beyonder battled various heroes, created a human body for himself, transformed a Manhattan office building into gold upon learning about the monetary system from a homeless woman and a hero-for-hire, learnt the difference between material goods which were meant to be ingested (food, cake) and those which were not (bottles), had a love affair with a disco star, got a haircut and wardrobe patterned after Michael Jackson circa Thriller, inspired a cult of meditators, was toilet trained by Spider-Man, and ultimately died when he tried to create for himself a human body without the intrusive omnipotence.
The tale of the Beyonder concluded several years later in an issue of the Fantastic Four where the characters learnt that the energy which comprised the Beyonder and the energy that gave the Molecule Man his powers needed to be combined in order to create the basis for a mentally stable, mature nigh-omnipotent being to be born.