Jon Hamm Jon Hamm

Oscar winner Kathy Bates, Jack Black and Mad Men's Jon Hamm will pop up in key guest spots this spring on NBC.

Bates will guest-star on The Office as the CEO of a company that acquires Dundler Mifflin. Bates — who will play a Southern charmer used to getting her way — will begin her multi-episode arc Feb. 4. The comedy will also welcome the birth of Pam and Jim's baby in a two-part episode airing March 4 and March 11. Jon Hamm will reprise the role of Liz's eccentric paramour Dr. Drew Baird on 30 Rock beginning Feb. 11.

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Fellow Thursday night comedy Community will feature Jack Black as a student eager to join the show's study group on Jan. 14. American Idol runner-up Katharine McPhee will play the stepdaughter of Pierce (Chevy Chase) and a possible love interest for Jeff (Joel McHale) on the first post-Olympics episode.

Emmy winner Michael Imperioli (The Sopranos) will check into Mercy on Jan. 13 as an outspoken hand-transplant patient who wants it amputated after discovering it used to belong to a pedophile. Debra Winger and Mischa Barton will appear on Law & Order and Law & Order: SVU, respectively. Winger will play a high school principal on the Jan. 29 episode and Barton will portray a pregnant prostitute who looks to Detective Benson for help on a yet-to-be-scheduled episode.

Who are you most excited to see?