Ultimate Marvel is an imprint of comic books published by Marvel Comics, featuring reimagined and updated versions of the company's most popular superhero characters, including Spider-Man, the X-Men, The Avengers and the Fantastic Four. However, the characters have new origins, freeing them from the sometimes convoluted back-histories of the original versions which were thought to turn off new readers unfamiliar with the continuity. Each character has been modified to reflect a more modern sensibility than their forebears which were originally created in the 1960s and 1970s. For example, Spider-Man gains his superpowers from a genetically-engineered spider rather than a radioactive spider, and his alter ego, Peter Parker, originally a photographer for the Daily Bugle newspaper, now has a part-time job as the paper's webmaster.
The imprint was launched in the 2001 with the publication of Ultimate Spider-Man. While Ultimate Spider-Man was originally aimed at younger readers in their teenage years, other titles in the Ultimate imprint have being aimed at older readers; however, all titles in the Ultimate imprint were intended primarily to attract new readers rather than to convert the existing Marvel fanbase. To go with the modern times, several things have changed in the characters backstories.
A noteworthy aspect of the Ultimate Marvel universe is that many of the characters are more youthful than their regular-continuity counterparts. In some cases, this is simply a result of taking the characters back to their origins - Spider-Man and the X-Men were teenagers at the beginning of their respective series - but other cases involve more striking changes. In particular, the backstory of the Ultimate Fantastic Four has been compressed so that they gain their powers when Reed Richards, the eldest, is only twenty-one years old, his role as father-figure of the group being transferred to the new character of Professor Storm, the actual father of Sue and Johnny Storm.
The characters in this line exist outside of the regular Earth 616 continuity of the Marvel Universe and therefore do not interact with their "original version" counterparts. There is some speculation in the comics industry and fandom that if the imprint continues to do well, the new incarnations of the characters in the Ultimate Universe may replace the "regular" Marvel Universe characters as the "official" versions of the characters.
Two writers noted for their work in the line are Brian Michael Bendis and Mark Millar. Former president Bill Jemas and Editor-in-Chief Joe Quesada were also deeply involved in the creation of the line.
Ultimate Marvel Timeline (http://www.sequart.com/ultimatechronology.htm)