Watch the skies.
A product of director Steven Spielberg and writer Harve Bennett, Invasion America (1998) is the first action-oriented "made for prime time" animated series that I can remember watching. Though not the first of its kind, FOX's The Simpsons, ABC's The Critic and USA's Duckman all precede it in that late night arena, the show was unique in both its presentation and clever mix of X-Files meets E.T. storyline.
The miniseries first aired on The WB's late night programming block and centered around a young man named who discovers that he's half alien and half human and (wait for it) must stop the two worlds from going to war against one another. While it may sound like your typical science fiction fare, the show was actually pretty well written and, despite falling into some of the Saturday morning 'toon dialogue, managed to last an entire season in a notoriously tough demographic.
Nonetheless the show has never seemed to find its audience and much like the recently deceased Heroes (NBC) series was left abruptly cut short. It was re-edited and broadcast on the Kids WB! programming, but once again failed to attract enough interest to justify any new episodes. Having re-watched it myself recently I can attest to the show's indecisive nature, as it tries to be relevant to both young adults and children, but also recall it being one of the only cartoons that my father and I could watch together during dinner. Besides, I'm willing to give it a few bonus points for being produced by the same studio that gave us the similarly ill-fated Toonsylvania (DreamWorks) and winning a Prime Time Emmy Award.