If you only know Megan Mullally for her Emmy-winning TV work as the gloriously egomaniacal Karen Walker on “Will & Grace” or as the sex-obesessed and plenty mean Tammy II on “Parks and Recreation,” well, prepare to be dazzled.

Mullally isn’t only a hilarious comedienne, but she’s also a helluva singer. She’s been on Broadway (“Young Frankenstein,” “How to Succeed in Business Without Really Trying").

And, in 2012, she joined forces with Stephanie Hunt — who played Devin Boland on “Friday Night Lights” — to create Nancy And Beth. Yup, that’s the eccentric name they gave their band, and they’ll perform Sunday at the Katharine Hepburn Cultural Arts Center. The show will be filmed for the TV series “The Kate.”

After this, Nancy And Beth will have July gigs at the Grand Ole Opry and the Newport Folk Festival. Not bad, eh? And they previously opened for Robert Plant and Emmylou Harris.

Mullally told NPR of their act, “We call it punk show-biz, because this show-biz element has crept into our very laid-back approach to music.” They put their unique stamp on songs including Gucci Mane’s “I Don’t Love Her” and George Jones’ “He Stopped Loving Her Today,” “One Mint Julep” and “Please Mr. Jailer.” Should be a fabulous show.

Nancy And Beth, 7:30 p.m. Sunday, Katharine Hepburn Cultural Arts Center, 300 Main St., Old Saybrook; 1-877-503-1286.