living out
loud

That voice may grate, but as kibitzing Karen on Will & Grace, Megan Mullally is winning a chorus of approval

Her part as Karen Walker, a tart-tongued, spoiled socialite water first conceived as simply the hapless assistant to interior Grace Adler (Debra Messing). But Mullal6y's on-camera antics--especially with Sean Hayes, who plays Jack McFarland, Will Truman's (Eric McCormack) campy friends have quickly made her a breakout star.

"Megan," says series cocreator Max Mutchnick, "is a world-class comedian who's got timing that's pure genius." Still, the 40-year-old Mullally is talking a modest game. She had been working almost two decades before landing the hit NBC comedy (Tuesdays, 9:30 P. M./ET) last fall. She lives in the same West Hollywood house she had rented for 12 years and, unlike spendthrift Karen, "never owned a piece of clothing that cost $14"--at least until now.

Things are definitely looking up for the only child of Martha, a former model, and Carter Jr., a retired Paramount Pictures contract player. "I'm really good at staying home all day in my pajamas because I had a [dad] who did that," recalls Mullally, who got her first taste of stardom in high school as a soloist with the local ballet troupe in her hometown of Oklahoma City.

She entered Northwestern University intent on acting, but her first class "horrified" her: "There was no way I was going to roll around on the floor pretending to be a bean or whatever." She switched majors to English literature (her living-room bookshelves are a reader's paradise), but became a campus star in spite of herself after lead roles in several musicals. When producers began calling, Mullally quit school and spent the next six years working in Chicago's booming theater scene.

In 1985 she moved to Los Angeles, where she quickly made her TV debut as the daughter on the short-lived Ellen Burstyn Show and landed small roles on such series as Seinfetd and Mad About You. "But I had a chip on my shoulder about Hollywood because I really wanted to do Broadway musicals," says Mullally, who finally realized her dream with lead roles in two hit revivals, "Grease" with Rosie O'Donnell in 1994 and "How to Succeed in Business Without Really Trying" opposite Matthew Broderick in 1995.

"I never made my peace with L.A. until after I'd done New York," says Mullally, who initially turned down the part of Karen because "it was just like the role Christine Baranski played on Cybill, this bored rich woman. If she'd been written in the pilot the way she is now, I would have been knocking people down to get it." But the producers persisted. "Megan was the only one we wanted," says cocreator David Kohan. Now, after some fine-tuning ("during the first table read I was improvising all this stuff that ended up in the script," she says), she's having fun playing "this completely clueless trophy wife who's happy as a clam." (Mullally was briefly married in the early '90s to Michael Karcher, now a CBS casting vice president.)