Sean Hayes and Rosie O'Donnell Join NBC's 'Hairspray Live!'

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Sean Hayes and Rosie O'Donnell are headed back to the '60s!

Announced at Hairspray Live's panel at the Television Critics Association summer press tour on Tuesday, the veteran actors will be joining the cast of NBC's live musical -- but who will they be playing?

NEWS: NBC's 'Hairspray Live!' Casts Amber Von Tussle and Link Larkin -- Find Out Who Scored the Roles!

Hayes will take on the role of Mr. Pinky, owner of the dress shop, while O'Donnell has been cast as the gym teacher.

And by the looks of their Twitter accounts, the actors couldn't be happier.

"I am so excited to be a part of #hairspraylive on @NBC! I can’t wait to bring it to life on December 7!!!" O'Donnell tweeted on Friday, followed by a similar post by Hayes.

RELATED: Kristin Chenoweth Is 'Excited' to Co-Star in NBC's 'Hairspray Live!'

News of Hayes and O'Donnell's casting follows NBC's Monday announcement that Dove Cameron and Garrett Clayton have landed the roles of Amber Von Tussle and Link Larkin, respectively.

The Hairspray newcomers join Kristin Chenoweth, Maddie Baillo, Harvey Fierstein, Jennifer Hudson, Martin Short, Derek Hough and Ariana Grande.

Hairspray Live!
will air Dec. 7 at 8 p.m. ET on NBC.