Megan Mullally reveals how Will & Grace's Karen found her voice

Will & Grace - Season 1
Photo: Andrew Eccles/NBC

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Will & Grace's Karen Walker is one of the most iconic characters in TV history, but actress Megan Mullally almost turned down the opportunity to play the self-centered millionaire.

"I had actually already auditioned for the role of Grace when they called me in to audition for Karen," Mullally says in the current issue of EW. "I didn't want to play the bougie best friend because I didn't think I could bring anything new to the part. Christine Baranski had just played the same kind of role on Cybill, but then I started thinking, 'I guess I could make her kind of weird.' "

At the first table read, Mullally began adding "honey"s and other ad-libs, but it was before actors were really allowed to improvise and she admits she was "a little scared" she would be fired.

"But they laughed, so I started to play around more — making her quirkier," she explains.

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Making Karen's voice higher was actually an evolution, and something Mullally says she "started doing without thinking."

"The pace of the show is quite theatrical, and my natural speaking voice is very laconic, so I thought, 'Well, I need to bring some energy to this character.' And I thought that was a good way to do it," she says.

But Mullally says she doesn't think she truly found who Karen was until episode 11 of season 1, where the main characters go to Champions on Ice and she has to sit next to an overweight woman who she calls a "loser."

"It wasn't in the script, but they just happened to have me sitting next to her, and so I just thought, 'Well, Karen is not going to want to be seated next to this woman,' so I started scooting away," she says. "The writers saw that and ran over and gave me a couple of lines to say to her. That was the beginning of the idea that Karen basically isn't able to bear anyone who isn't her."

Will & Grace airs Thursdays at 8 p.m. ET on NBC.