Comic-Con: Samuel L. Jackson And Charlize Theron Join 'Astro Boy' Voice Cast

Astro BoyI'm here in Hall H, where the room is packed with shrieking "Twilight" fans and the geeks that are trying their best to not have their ears shattered. Some big news, however, has already been made by "Astro Boy," the new adaptation of a sci-fi cartoon classic.

Moments before unveiling the eye-popping new trailer for the flick, Summit (the studio releasing "New Moon" and "Astro Boy) announced that two new actors had signed on to join Nicolas Cage, Kristen Bell, Freddie Highmore and the rest. And they ain't lightweights.

Samuel L. Jackson and Charlize Theron will be loaning their familiar pipes to the fall flick. Although it was not revealed which characters they'll be playing - and they could not be heard in the trailer- both are expected to voice prominent characters.

The trailer for Astro-Boy featured some amazing CG-animated footage of the boy robot, an enormous "Peacekeeper" evil robot, and even depicted a moment when Astro Boy comically discovers that he has machine guns in his butt. The clip also took the relatively-rare Comic Con approach of revealing several unfinished shots, encouraging fans to use their imagination.

Stay tuned to MTV News for further developments on Samuel L. Jackson and Charlize Theron's roles in "Astro Boy," as well as other breaking Comic-Con news.