It seems television will be full to the brim with exciting guest stars on some of the most popular shows this season.

Kelsey Grammer (Boss) will be returning to NBC’s 30 Rock when the show returns this spring. Grammer previously played himself in cahoots with Jenna (Jane Krakowski) and Kenneth (Jack McBrayer) to scam free ice cream from Carvel. He’ll be joining them once again for another heist.

Megan Mullally (Will & Grace) will be stopping by for a guest spot on NBC’s Up All Night, as Ava’s (Maya Rudolph) rival talk show host, Shayna Mund. The character used to be Ava’s protege but is now cutthroat to beat her in ratings. (And this Wednesday, catch Molly Shannon guest starring as Reagan’s (Christina Applegate) incompetent assistant.

Laura Benanti (The Playboy Club) will guest star on Law and Order: SVU as Detective Nick Amaro’s (Danny Pino) wife, which will possible become a multi-episode arc.

Kiernan Shipka (Mad Men) will play herself on ABC’s Don’t Trust the B— in Apartment 23, alongside James Van Der Beek (Dawson’s Creek), who plays himself in the series. The episode will have the two sign on to do a movie together.

Derek Webster (Damages) will replace Joseph C. Phillips in Castle, as the New York City mayor. He will take over in early 2012.