Sean Hayes, he of Will & Grace fame, and Rosie O'Donnell are joining NBC's Hairspray Live!, a special musical event set to air later this year.

Hayes will play shop owner Mr. Pinky and O'Donnell is set as the gym teacher, producers announced at the Television Critics Association gathering in Beverly Hills Tuesday.

They'll join a cast that includes Harvey Fierstein, who won a Tony for his performance as Tracy's mother Edna in the original Broadway production. Ariana Grande will play Penny Pingleton, the goofy best friend of central character Tracy Turnblad (newcomer Maddie Baillio). NBC recently announced the addition of Dove Cameron, a star of Disney Channel's popular series Liv and Maddie, who has been cast as Amber Von Tussle, while Garrett Clayton will play Link Larkin.

Kristin Chenoweth, Martin Short, Jennifer Hudson and Derek Hough also star.

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Hairspray Live! follows the story of Tracy Turnblad, who dreams of dancing on the fictional The Corny Collins Show, a local TV program. Tracy wins a role on the show, becoming a celebrity and meeting characters including the hunk Link and Seaweed, an African-American boy she meets in detention. Tracy's mother is the indomitable Edna, and she eventually encourages Tracy on her campaign to integrate the all-white Corny Collins Show.

Hairspray Live! airs Wednesday Dec. 7 on NBC.