"30 Rock" stars Tina Fey and stage regulars Alec Baldwin, Jane Krakowski, Tracy Morgan and Jack MacBrayer.
Jackson, who has also been seen on television in the Fox musical comedy "Glee," has appeared on Broadway in Finian's Rainbow, Xanadu and All Shook Up, among others. He has appeared Off-Broadway in Altar Boyz and The Agony and The Agony, and at City Center in Finian's Rainbow and Damn Yankees.
"30 Rock" airs Thursday nights at 8:30 PM ET on NBC.