Oprah Winfrey walked on stage at Chicago's United Center on Tuesday night to receive a standing ovation from thousands of her fans and greetings from Tom Hanks, Tom Cruise and Madonna.

"You always had the power, and that is the message you brought into our lives," Cruise told Winfrey.

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Clint Asaph shows off his painting of Oprah Winfrey as fans wait for the taping of the finale of The Oprah Winfrey Show at the United Center in Chicago. (Charles Rex Arbogast/Associated Press)

Hanks told her that her fans just wanted to say thank you "for what The Oprah Winfrey Show has meant in our lives."

Winfrey announced in November 2009 that she would end her show this season after 25 years.

The guest lineup for Surprise Oprah! A Farewell Spectacular was a secret, but the show quickly delivered on promises from Winfrey's producers that the biggest names in Hollywood would be there.

Tuesday's taping will air May 23 and 24, before Winfrey's final show on May 25.

Madonna told the crowd that she is among the millions of people who are inspired by Oprah.

"She fights for things she believes in, even if it makes her unpopular," Madonna said.

Josh Groban and Patti LaBelle sang Somewhere Over the Rainbow as Winfrey, in a long purple dress, sat in a white chair onstage.

"Was that not the coolest?" Winfrey said when they finished.

Actor Will Smith introduced Michael Jordan, describing the United Center as the "house that Michael Jordan built."

Jordan came on stage and hugged Winfrey to loud cheers. The basketball legend led the Chicago Bulls to six NBA championships during the 1990s.

Winfrey yelled to the crowd, "M.J. is in the house!"

Jordan told Winfrey she has meant a lot to him and inspired him. He wished her the best and told her he loves her.

The arena was decorated with pictures of Winfrey at seminal moments over the course of the talk show. Boxes of tissues were on scattered seats throughout the audience. The guest lineup for Surprise Oprah! A Farewell Spectacular was kept secret, but Winfrey's producers have promised the biggest names in music, movies and television.

Fifty-two-year-old Cathy Deters of Cincinnati was one of hundreds who lined up outside the United Center before the taping began. She drove to Chicago without a ticket, but someone outside gave her one. The energy broker says she doesn't think anyone can replace Winfrey.

The United Center, which is home to the Chicago Bulls and Chicago Blackhawks, has a seating capacity of more than 20,000. It is just blocks from Winfrey's long-time studios.

Harpo Productions received more than 154,000 ticket requests for seats to Tuesday's event. Tickets were free and distributed to fans through a lottery.   

Oprah's producers say celebrities have been quick to accept invitations to appear in the final shows.

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Showing Oprah painted on her head, Victoria King from Chicago waits in a lineup to get into the taping of The Oprah Winfrey Show's finale at the United Center in Chicago. (Charles Rex Arbogast/Associated Press)

"Celebrities from film, television and music feel a deep appreciation for the support they have received from Oprah and the show over the years," executive producer Sheri Salata said. "Oprah will be very touched by that gratitude."   

The content of the final episode of The Oprah Winfrey Show is still under wraps. Winfrey announced in November 2009 that she would end her popular talk show after 25 years.   

"Oprah is in great spirits, energized and taking in every last bit of these final days," said Salata. "The producers are a little teary-eyed — it's hard to say goodbye."