Mariah Carey

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4. Mariah Carey
Pop superstar Mariah Carey has been no stranger to The Oprah Show—she's been featured 22 times! Mariah has helped make many viewers' dreams come true, and in 2005, she coached one of her biggest fans, 12-year-old Paul, through his first recording session. Paul ended up landing a record deal, and Mariah signed on as the producer!

Oprah has also recognized Mariah's history-making accomplishments in the music industry. In 2008, Mariah topped the charts with her 18th number one hit, breaking a record previously held by the one-and-only Elvis Presley.

How well do you know Mariah? Take the quiz!