In 1988, Oprah interviewed Elizabeth Taylor, who specifically requested the talk show host to refrain from discussing her seven marriages. Winfrey teased, "I declare, you've got to stop talking so much, Ms. Taylor!"
In 1993, Oprah ventured off to Michael Jackson's Neverland Ranch for his first interview in 14 years.Jackson revealed candid details about his skin color, plastic surgery, his relationships and children.
Mary Tyler Moore
One of Winfrey's role models is Mary Tyler Moore's character — an independent, career-minded woman — on "The Mary Tyler Moore Show." In 2008 "The Oprah Show" recreated Tyler's set on the Harpo Studio stage and invited the entire cast.
In 2006, Book Club author James Frey admitted he invented and embellished parts of his memoir, "A Million Little Pieces."Oprah confronted him on her show and said, "I feel duped, but more importantly, I feel that you betrayed millions of readers."Frey's career has since recovered, but he lost a book deal in the aftermath.
As the first African American actor to receive an Academy Award, Sidney Poitier visited Oprah's show in 2000, after his autobiography was published.Oprah said she had watched him receive his Oscar as a 10-year-old girl and was inspired. She later wrote o her website, "I remember thinking that if he could do that, I wonder what I could do."
Oprah had said she always dreamed of singing onstage with superstar Tina Turner on stage. Her dream came true during her 2000 launch party for her magazine, "O, The Oprah Magazine."
In a shocking interview, Mackenzie Phillips appeared on the show and spoke for the first time about her incestuous relationship with her musician father, Jon Phillips in 2009.Phillips wrote a book called, "High on Arrival," which describes her struggle with drugs and the relationship with her father.
Lady Gaga, recently topping Ms. Winfrey on the "Forbes Most Powerful" list, performed on the "Oprah Show" in January 2010.
In one of the most memorable and talked about episodes from 2005, an ecstatic Tom Cruise jumped up and down on Winfrey's couch, proclaiming his love for Katie Holmes.The episode sparked criticism of the actor and many questioned Cruise's bizarre behavior.
Oprah's 1986 interview with extraordinary pianist, Liberace, was his last — as he died of AIDS-related complications six weeks later.Winfrey has called him one of her favorite guests.
In a much-anticipated show, Oprah announced Kirstie Alley would lose weight and show off her slimmer body wearing nothing but a bikini.The actress kept her promise and in November of 2006 strutted down Winfrey's stage wearing a brown two-piece.
Lisa Marie Presley
In 2005 Lisa Marie Presley sat down with Oprah to discuss her difficult teenage years, struggle with drugs, and short-lived marriage to Nicolas Cage.
Whitney Houston opened up to Oprah in a 2009 interview and disclosed her tumultuous 14-year marriage to Bobby Brown and battle with drugs.
Chris Rock made his "Oprah Show" debut in 1997, and is one of Oprah's all-time favorite guests. Oprah said, "I just love the way his mind works."
World famous singer, Celine Dion, goes down as Oprah's most frequent celebrity guest — appearing on the show 27 times!Dion first appeared on The Oprah Show in 1996 after Oprah surprised the entire audience with a trip to Disney World.