In the years since Megan Mullally became an Emmy-winning sitcom favorite as the nasal-voiced narcissist Karen Walker on NBC's long-running Will & Grace, she's refused to be categorized, even as she's set to reprise Karen on NBC's forthcoming reboot of the ground-breaking comedy.

Last year, she played the buttoned-up mom type in the James Franco comedy Why Him? And she is getting great reviews for her next pairing with the prolific actor-director, in the much-anticipated The Disaster Artist. She's reveled in the weird on television series, such as cult favorites Bob's Burgers, Party Down, and Childrens Hospital. And on stage, she busies herself with actor-husband Nick Offerman (better known as Ron Swanson on Parks and Recreation) on tart musical comedy productions like Summer of 69: No Apostrophe, which brought them to the Merriam Theater last year.

And, now, she'll play a rock star as one half of Nancy and Beth, Mullally's dulcet -- and comically vaudevillian -- musical duo with thespian-singer Stephanie Hunt. "It's a little more of an all-singing-all-dancing-revue than when Nick and I go on tour," says Mullally.

The vocal pair release their eponymously titled debut album Friday and will appear at World Cafe Live on Tuesday, and again next month for that venue's NON-COMM music convention (May 17-19).

"I like duos, what can I say?" she says of pairing with Offerman, Hunt, and even Sean Hayes on Will & Grace. "I enjoy being with that one right person. Even my hobby as an interior designer involves just one friend. The point is, though, to not have just one fixed role. Like, we both choose the songs in Nancy and Beth, and I think our voices, our harmonies, blend seamlessly."

Mullally, who is 30 years her partner's senior, believes she and Hunt are of one mind.

"When we love a song, we just snap our heads toward each other with wide eyes. We just do things in a psychic way without talking. The only thing that happens separately is that I am fully responsible for the choreography. Every song has its own individual dance steps," Mullally says. "It's showbiz with an exclamation point, even though we -- as singers -- are more raw, and not at all showbizzy."

After meeting in Austin, Texas, in 2012, Mullally and Hunt -- the lead singer in the Ghost Songs and an actress with credits in Friday Night Lights, Californication, Glee, and Somebody Up There Likes Me -- found immediate symbiosis as musical forces. They never wanted to do the same sound twice or be repetitive. "We bore easily," says Mullally.

Listen to their debut recording or the devotional, YouTube-only ballad "The Cool of the Day," and no song sounds like the next -- not when they cover Rufus Wainwright's lonely "Vibrate" or Gucci Mane's sad but sensual "I Don't Love Her" -- save for their silken, silvery harmonies shining bright.

This is hardly the stuff of comedy. Yet there is something goofy about the debut album, which is exploded by the whole hat-and-cane routine of the Nancy and Beth stage show. "You can't stay poignant all the time," Mullally says with a laugh. "It's not a comedy band, yet we are funny in a free-form, disassembled, show-biz way, if that makes sense."

Mullally says overanalyzing Nancy and Beth is not the way to go. "We're really just like two little girls playing in a tree house."

Before disappearing for a Summer of 69 performance ("Nick's been here the whole conversation"), Mullally can't leave without discussing the soon-to-lens Will & Grace reunion, a wildly loved show that ended in May 2006. It returned as a left-leaning get-out-the-vote video short last year with the entire cast, its cocreators (David Kohan, Max Mutchnick), director (James Burrows), and crew intact. That short film's mega-success demanded that another full season of Will & Grace was in order with Mullally and her former costars. "We start filming in August, 11 years after we stopped, and it feels as if we just went away for the weekend. It's bizarre," says Mullally.

Ask her whether the new Will & Grace will be politicized in the same way the short was. Mullally's Karen supported Trump, Will and Grace supported Clinton, and they tried to sway Hayes' Jack to vote for their candidate. The debate ended when Jack discovered Katy Perry was Hillary all the way. Mullally says the first objective, as always, is to be funny. "The writers and creators never politicized anything, really, including the fact that Will and Jack were gay, right? Will & Grace, however, was always topical, and since all things Trump have taken over, who knows?"

Nancy and Beth, 8 p.m. Tuesday, World Cafe Live, 3025 Walnut St., $28,

Nancy and Beth also play as part of the 17th annual NON-COMMvention, May 17-19, World Café Live.