According to Simpsons producer Al Jean she “plays a little girl who becomes Lisa’s best friend, but then she kinda goes crazy. Thanks to Sam for the news.
Denis Leary, Emily Blunt and Seth Rogen. These are just a few of the guest stars Matt Groening has signed for the 20th season of The Simpsons, which bows in September.
If you haven’t yet heard, Seth is not only guesting, but wrote the episode he’s lending his voice to. The storyline? Comic Book Guy creates a superhero that gets made into a movie character. Homer lands the lead role in the film, but is told he has to slim down first. He hires a personal trainer — voiced by Rogen — and gets in shape, but after filming is completed, he can’t afford to keep the trainer anymore and all his hard work goes to hell, of course.
Source: Zap 2 It