Superman (real name William "Bill" Dunn) was a character that appeared in the short story The Reign of the Superman. Despite acting as the initial version of the DC Comics hero that's well known, this Superman, was in fact intended to be a villain protagonist.
Bill Dunn was initially merely a poor man who was waiting in a bread-line each and every day. However, he was singled out by a misanthropic scientist named Professor Smalley, and took him for a hot meal. He then recruited Dunn to be part of an experiment regarding a strange meteorite. The exposure resulted in him gaining powers of telepathy, mind control, and telescopic vision. However, it came at the cost of corrupting the man, turning him into a supervillain and renaming himself the Superman.
He then aimed to conquer the world with his new powers upon experimenting with his powers. As preparations for the conquering of the entire world, he then proceeded to sow discord in the world via his mind manipulation abilities.
Professor Smalley, however, desired to gain those powers, causing them to have a final battle. Superman proceeded to kill his "creator.".
Unfortunately, the victory was Pyrrhic at best, since it resulted in his powers being drained and the formula for retaining said powers being gone for good. Now back to Bill Dunn, he is forced to go back to the bread-line.
As noted above, this is the first Superman incarnation, with most later incarnations being heroic.
Unlike the mainstream Superman, who was of alien origin and was more physical in his strength, this Superman was an enhanced human and more mental-based. Ironically, this rendition of Superman resembles the iconic Lex Luthor in terms of physical appearance.
Jerry Siegel and Joe Shuster, the men who wrote and drew the story and later the Superman character when he was reinvented as a superhero, conceived of the character and story initially as a criticism towards German philosopher Friedrich Nietzsche's idea of the ubermensch (which translates from German into either "Overman" or, in this case, "Superman") that was voiced in his work Thus Spoke Zarathustra.