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Dr. MEHMET OZ
The New York Presbyterian cardiac surgeon first appeared on The Oprah Winfrey Show in 2004, making regular appearances as the talk-show host's resident health expert. After discussing health-related issues – from stem-cell research to the proper way to pop a pimple – the Harvard-educated doctor was awarded his own show in 2009: The Dr. Oz Show, backed by Winfrey's Harpo Productions.
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The plucky, popular Food Network host scored her own deal with Winfrey's star-making Harpo Productions in 2005, promoting her eponymous show with appearances on Winfrey's own talk show. "Rachael's energy and ability to connect with her audience are why she's such a hit," Winfrey tells PEOPLE of her protégé, who went on to win an Emmy and (just like Oprah) launch her own magazine, Every Day with Rachael Ray.
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DR. PHIL MCGRAW
After a show about the mad cow disease scare prompted beef producers to sue Winfrey in 1995, the talk-show host hired Dr. Phil's legal consulting firm to prepare her for the trial. The no-nonsense psychologist made such a strong impression that Winfrey invited him to appear on her show. He eventually became a regular guest, earning his own syndicated show (produced by Harpo). "He has the foresight and skill to look at any situation, cut through the psychobabble, and call it as he sees it – and he's usually right," Winfrey wrote in O magazine.
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The financial advisor first caught the attention of Winfrey with her interactive television show, Can I Afford It?, where Orman counseled callers on aspirational purchases. A regular guest on The Oprah Winfrey Show, Orman also has a monthly column in O magazine and she costars with fellow Oprah protégés Dr. Phil and Dr. Oz on the viewer-advice show, Ask Oprah's All Stars, airing on OWN.
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When Winfrey backed Rhonda Byrne's self-help film and like-titled book in 2007, it immediately shot to the top of bestseller lists on Amazon and the New York Times. "The message of The Secret is the message that I've been trying to share with the world," Winfrey told Larry King, saying that she used the book's "Law of Attraction" method to help win her role in The Color Purple.
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Professional organizer Walsh, whose appearances on de-cluttering your home have earned him his own show, Enough Already!, on Winfrey's OWN network, is one of the talk-show host's newest superstars. "Everybody has a mess going on somewhere," Winfrey told Parade.
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DR. LAURA BERMAN
The sex and relationship expert is also getting her own show on Winfrey's OWN network. Explains Winfrey: "Every time I do Laura Berman on the show I feel like, 'Ugh, I really don't want to be discussing this on daytime television,'" Winfrey has said of Berman's, ahem, adult subject matter. "Finally she has a space to do that kind of talk."
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The interior designer first teamed up with the media powerhouse in 2008, as the host of her philanthropy challenge show, Oprah's Big Give. But his partnership with Winfrey didn't end there: he landed his own syndicated show, The Nate Berkus Show. "We brought him here because of his incredible eye for style, and we grew to love him for his big ole heart," Winfrey said during his last appearance on her show. "He taught millions of us to love the way we live."
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Winfrey calls the poet and author "mentor-mother-sister-friend" – and helped turn Angelou into a household name, thanks to numerous appearances on her show and early inclusion in Oprah's Book Club. "She's the woman who can share my triumphs, chide me with hard truth and soothe me with words of comfort when I call her in my deepest pain," Winfrey wrote in O magazine..
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She can sell millions of books, launch careers, and fill an entire network with new shows – but can Winfrey pick the president? Some say yes. Before Barack Obama even decided to run for President, Winfrey threw her support behind the junior Senator – and stumped for him in her "Oprah-bama" tour in 2007. "If he wants me to, I'm ready to go door to door," Winfrey later tells Entertainment Tonight, after Obama beats former front-runner Hillary Clinton for the Democratic nomination.
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