Ultimate War is a comic book limited series produced by Marvel Comics featuring the Ultimates and the Ultimate X-Men. The series contains four books, released between December 8, 2002 and February 23, 2003. It was written by Scottish comics author Mark Millar with art by Chris Bachalo.It is collected as part of the Ultimate X-Men series of trade paperbacks. This was the first time the Ultimates as a team had crossed over with characters from the Ultimate Marvel Universe.