Jack Black Guest Star Neil Patrick Harris Guest Star LL Cool J Guest Star Will Arnett Max the Magician Guest Star Fran Brill Zoe, Prairie Dawn Voice Chris Brown Guest Star Leslie Carrara-Rudolph Abby Cadabby Voice Kevin Clash Actor John Legend Music Performer Eric Jacobson Bert, Grover Voice Steve Whitmire Actor Jerry Nelson Actor Joey Mazzarino Stinky, Murray Voice Carmen Osbahr Rosita Voice David Rudman Baby Bear, Cookie Monster, Two-Headed Monster Voice Molly Shannon Guest Star Patrick Warburton Guest Star Diana Krall Music Performer Jonah Hill Guest Star Caroll Spinney Big Bird, Oscar the Grouch Voice