In 1999, Simonson returned to Marvel to write a "Warlock" series, which featured a character from her previous "New Mutants" run. That same year, she wrote a miniseries, "Galactus the Devourer", in which Galactus died temporarily. In 2005, she wrote stories featuring Magnus, Robot Fighter for the publisher Ibooks, Inc. In 2007, Simonson wrote a one-shot starring Magik of the New Mutants as part of a four-issue event known as "Mystic Arcana". In 2009, she wrote two issues of "Marvel Adventures" featuring Thor. The next year, she scripted the five-part limited series "X-Factor Forever" and reunited with June Brigman for a new "Power Pack" story in "Girl Comics" #3. Simonson also co-wrote the comic "World of Warcraft", based on the multi-million player internet game, for Wildstorm, and a manga story, based in the Warcraft universe, for Tokyopop. In 2011, DC hired Louise Simonson to write "DC Retroactive:" "Superman - The '90s", pencilled by her "Man of Steel"-collaborator Jon Bogdanove.