Jan Hooks, a versatile comic performer who stole scenes during one of the glory eras of “Saturday Night Live,” died Thursday at 57, her agent’s office confirmed.

Sources told the website TMZ that Hooks had been battling a serious illness and died Thursday morning.

“Man, she was good,” former “SNL” writer Bob Odenkirk said in an email, calling Hooks “the best there could be at sketch.”

During her 1986-91 stint on “SNL,” which followed a small role in the film “Pee-wee’s Big Adventure,” she performed with Nora Dunn as half of the medley-crooning Sweeney Sisters and as Hillary Clinton to Phil Hartman’s Bill. She also played Sinead O’Connor in a famously savage sketch called “The Sinatra Group,” hosted by Hartman as a snarling Chairman of the Board. Despite her confidence onscreen, she was always hiding her apprehension.

“I have crippling stage fright,” Hooks said in a 2013 interview. “And I never, ever enjoyed the live quality of that show.”

“And sometimes if I see an old show, I think, ‘Boy, I was good!'” she added. “I mean, you can’t tell how s–t-scared I was. You know how they say, ‘Oh, everybody’s got the jitters, and then you get out there and you’re fine?’ No! I wasn’t! I didn’t like it! I don’t like roller coasters, and I don’t like circus performing. It’s just not my thing.”

It didn’t stop her from standing out in nearly all the roles she played. One of her most beloved (also alongside Hartman, a frequent on-camera cohort) was in a short romantic film titled “Love is a Dream,” which initially played in the typically uneven final half hour of “SNL.” Written and directed by Tom Schiller and shot by cinematographer Neal Marshad, the wistful fantasy features Hooks and Hartman waltzing to a Bing Crosby tune and was a chance for both to show off their dramatic acting chops.

“A lot of the cast came from standup comedy, which is more boisterous and aggressive,” Schiller told the Sun-Times. “And [Jan] came from an acting standpoint. One of her heroines was Bette Davis, who took her career seriously. And I think Jan took hers seriously.”

Once, when Hooks was slated to play Davis on “SNL,” Schiller watched her prepare backstage.

“You could see her transforming herself and taking time before the camera opened up,” he said. “But I don’t think a lot of the other actors really invested that much craft as she did.”

“She was always a very sweet person,” Schiller added. “She wasn’t phony or an avaricious showbiz type, climbing her way to the top. She was funny and intelligent and a joy to work with.”

After “SNL,” Hooks became a regular on CBS’s “Designing Women” and did guest spots on “The Simpsons” as well as NBC’s “3rd Rock From the Sun.” In 2010 she appeared as Jenna Maroney’s scheming mother Verna on “30 Rock.” But her years at “SNL” were seminal.

“I had a huge ego,” Hooks recalled of her early years in the “SNL” oral history Live from New York. “I just loved anybody that wanted me to show my stuff. I will do it. Oh man, let me go out there and show my stuff. And in my mid-twenties, it kind of hit that it wasn’t a hobby anymore, that it was my vocation, that I had to do this in order to live. And that shaded it in a whole different way. It made me afraid, you know?”

“Frankly, I kind of miss those silly years of youth, where you’re all ego and you just want to get out there and show your stuff.”

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