She has built her fame and considerable fortune by baring her soul to a nation of telly addicts almost daily.
But despite her carefully cultivated "woman of the people" image, Oprah Winfrey takes a dim view of any outsider impertinent enough to wonder what makes her tick.
That is the verdict of celebrity biographer Kitty Kelley, one of the book industry's foremost scandalmongers, who claims the magisterial chat-show host's personal privacy is protected by a wide-reaching brand of media censorship.
Kelley, who has swung a hatchet at Nancy Reagan, Frank Sinatra, and the royal family, will tomorrow publish an unauthorised biography of Winfrey, which is expected to delve into her abusive childhood and somewhat mysterious sex life.
It will have a print run of 500,000, and has generated sufficient buzz to be already in the top 25 of Amazon's sales charts.
But unlike almost every other biography of Kelley's career the launch of Oprah has attracted virtually no interest from TV channels.
Every American network - with the exception of NBC, which will have her on the Today show - is reported to have decided not to feature the author in its programmes.
Kelley blames the blackballing on an industry paranoia about upsetting Winfrey.
"We have already been told by Barbara Walters' producer 'no, you cannot be on The View. I cannot disrupt my relationship with Oprah'," Kelley told the New York Times.
"Joy Behar, the same thing. Charlie Rose; Larry King said 'I will not do it, it might upset Oprah'. Even David Letterman."
A spokesman for Kelley, who interviewed roughly 850 of the TV presenter's acquaintances during three years of research for the book, said the networks that refused to invite Kelly on air had "cited sensitivity to their relationship with Ms Winfrey".
The TV stations are perhaps right to be cautious - Kelley is a formidable and very thorough disher of celebrity dirt whose book reportedly presents Winfrey as "a cold manipulator who requires everyone around her to sign confidentiality agreements".
The book will also delve into the tough Mississippi childhood to which Winfrey occasionally refers, but about which she is notoriously sensitive. She was sexually molested and at the age of 14 had a son who died in infancy.
Says Kelley: "This book names the little boy, presents the birth certificate and tries to show how these awful secrets controlled Oprah for most of her life."
* Frank Sinatra: Tried to sue over Kelley's portrayal of his links to organised crime
* Nancy Reagan: Kelley told readers Reagan lied about her age and had several affairs.
* George W Bush: Kelley alleged Bush was in the habit of snorting cocaine at Camp David during his father's time in office.
Kim Hill is interviewing Kitty Kelley this Saturday on Radio New Zealand National.