Ultimate Marvel debuted with Ultimate Spider-Man #1 (September 6, 2001)
The idea for the Ultimate imprint was developed by Bill Jemas. In his perspective, the main problem of Marvel Comics was that it was “publishing stories that were all but impossible for teens to read — and unaffordable, to boot”. He worked on an idea given by a CEO of the Wizard magazine: reboot the heroes back to their original character premise.
The working title for the imprint at that point was “Ground Zero”. Unlike previous reboots, there was no in-story explanation for the existence of the imprint, and the standard comic books were still being published, unaffected by the new project. Thus, Ultimate Spider-Man would contain the stories of a new teenager Spider-Man starting his career, and the usual Spider-Man titles would still contain the stories of the adult Spider-Man with sixty years’ worth of continuity. Quesada then hired Brian Michael Bendis, an artist from indie publishers, for the first comic book of the imprint, Ultimate Spider-Man. He changed the narration style so that it resembled a TV series more than a classic superhero comic book. There were no thought bubbles or long expositions, and the first issue did not feature any superhero costume.