LOS ANGELES >> In the two years since Channing Dungey took over as president of ABC Entertainment, becoming the first black executive to run a major network, she had largely eschewed the spotlight, avoiding public comments whenever possible and preferring that her work speak for itself.

She has certainly made her voice heard now.

Dungey today announced the firing of Roseanne Barr, one of ABC’s most important stars, after the incendiary comedian posted a racist tweet about Valerie Jarrett, a former top adviser to President Barack Obama.

“Roseanne’s Twitter statement is abhorrent, repugnant and inconsistent with our values, and we have decided to cancel her show,” Dungey said in a statement.

Dungey did not make the decision alone. Her boss, Ben Sherwood, president of the Disney-ABC Television Group, and his boss, Robert A. Iger, Disney’s chief executive, also backed the cancellation of “Roseanne,” which returned with monster ratings in March after concluding its initial run in 1997.

But it was striking that it was Dungey and not one of her superiors — and not a network spokesman or spokeswoman, to whom such statements are often attributed — who condemned Barr and declared the end of “Roseanne.” Dungey, 49, became an instant celebrity, her name trending on Twitter as people rushed to express gratitude for her stand and holding her up as an example of why diversity in Hollywood’s highest ranks is important.

Stars like Viola Davis, who headlines the ABC drama “How to Get Away With Murder,” and Tony Goldwyn, who appeared on the ABC series “Scandal,” offered their applause. Krista Vernoff, a producer of “Grey’s Anatomy,” the long-running ABC medical drama, said in a Twitter post, “THANK YOU Channing Dungey for being my one little slice of hope for our country today.”

“Sitting on top of your world like a Queen in full judgement of your garbage and taking it out,” filmmaker Ava DuVernay, who most recently directed “A Wrinkle in Time” for Disney, wrote of Dungey on Twitter.

Dungey grew up in Sacramento, California — her sister is actress Merrin Dungey, known for her TV work on “The King of Queens” and “Alias” — and graduated from the University of California, Los Angeles, where she studied film and television. She got her start in Hollywood in the early 1990s, developing movie ideas at 20th Century Fox and then becoming a story editor for Steven Seagal’s company, which was based at Warner Bros. Dungey soon became a Warner production executive, working on films like “Twister,” “Space Jam” and “The Bridges of Madison County.”

She joined Disney in 2004 as an executive at what was then Touchstone Television, where she helped develop “Criminal Minds” for CBS and played a major role in the early production of “Grey’s Anatomy.” Her dogged advocacy for that medical drama, created by a then-unknown Shonda Rhimes, became an asset as Rhimes rose to prominence as one of Hollywood’s most important show creators, with hits like “Scandal” and “How to Get Away With Murder.”

Along the way, Dungey won fans in Hollywood’s broader creative community by delivering feedback in a manner that managed to be both blunt and compassionate. She also became known for a quiet resolve — standing out by not joining other television executives in public grandstanding, even when she made history as the first black network president.

“I’m humbled by the great things that people have said,” Dungey told the Los Angeles Times in 2016 when she replaced Paul Lee as ABC’s chief. “In terms of looking at this as maybe being a role model, I’ve always been very focused on being a role model for my daughter. And if I can inspire young women to pursue a career path in entertainment because of this, that would be a wonderful thing.”

Dungey has encountered her share of difficulties — some involving diversity — since taking over as president of ABC Entertainment, a job that gives her oversight of prime-time and late-night programming, marketing and scheduling.

She was criticized (along with Sherwood) for putting the rebooted “Roseanne” on the schedule in the first place, especially after the uproar over an episode’s joke about the minority-led comedies “black-ish” and “Fresh Off the Boat.” In a blow to ABC, Rhimes decamped to Netflix in August after the streaming service gave her a lucrative multiyear deal.

And ABC’s relationship with another important minority show creator, Kenya Barris, has deteriorated in recent months. This year, ABC pulled an episode of his show, “black-ish,” that examined race relations in America in pointed fashion. During a conference call with reporters this month to discuss ABC’s fall schedule, Dungey said the decision to pull the episode had been mutual.

“I think we all feel like that was the best decision overall,” Dungey said.

ABC and Barris may ultimately decide to part ways. He has been talking to Netflix about a deal of his own. But Barris was among those who took note of Dungey’s censure of Barr. In tweeting a link about the cancellation of “Roseanne,” he said “Bye-bye!!!” and included Dungey’s name and the emoji for gratitude.