The landmark 21st Season of The Simpsons will premiere on FOX September 27 at 8:00 PM (EST) with “Homer The Whopper” (originally intended to air in Season 20).
Here’s the episode description from SimpsonsChannel.com:
Comic Book Guy casts Homer as the lead in “Everyman,” a feature film based on the new comic book superhero he created. To whip him into shape for the part, the movie studio hires celebrity fitness trainer Lyle McCarthy (guest voice Seth Rogen [who also co-wrote the episode]) but Homer has trouble sticking to his new, healthy regimen.
Furthermore, WorstPreviews.com has details on other guest celebrity voices featured in the upcoming season:
Jonah Hill guest-voices as “Andy,” a former Springfield Elementary student hailed as the best prankster ever in the upcoming episode, “Pranks and Greens.” Neve Campbell plays “Cassandra,” a Wiccan accused of blinding the town with a spell (a la “The Craft”) in “Rednecks and Broomsticks.” Jackie Mason returns as Rabbi Krustofsky, Krusty the Clown’s father, in “Once Upon a Time in Springfield,” in which Krusty ends up falling in love with the actress who plays “Princess Penelope” (guest star Anne Hathaway), a new character on his show. The late Eartha Kitt also lends her voice talents to the episode.
Additional guest stars paying Springfield a visit next season include Coldplay’s Chris Martin, Sarah Silverman, football greats Eli Manning and Peyton Manning, sportscaster Bob Costas, UFC champion Chuck Liddell and actress Angela Bassett.