Josh Brooks (Tommy Peterson)
I'm guessing this kid was originally intended to be a main character if the show had immediately gone to series after the original four-hour TV movie. He would have been the show's resident orphan, a constant reminder of the horrors of the invasion. I can't think of another reason that he's billed up front with the rest of the main cast, rather than with the guest stars. He only has two or three scenes.
When they went to the second miniseries, they dropped his character altogether.