As Elizabeth Taylor's family arranges for a private funeral to take place later this week, her celebrity friends and admirers are paying their respects to the legendary actress, who died in L.A. Wednesday at the age of 79.

"We have just lost a Hollywood giant," close friend Elton John, 63, told CNN in a statement. "More importantly, we have lost an incredible human being."

(John and Taylor have both been tireless advocates for HIV/AIDS awareness.)

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Adds pregnant songbird Mariah Carey, 41: "R.I.P. Elizabeth Taylor an incomparable legend who will live forever."

"Sad to hear of Elizabeth Taylor's death," Joan Rivers, 77, tweeted. "She was the first major celebrity to join me in the fight against AIDS when it wasn't a popular cause."

"Elizabeth, thank you for the lessons you taught me about life, suffering and joy," Kirstie Alley, 60, wrote. "You are the BRIGHTEST STAR in the universe. Eternal love."

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"I am so saddened about the passing of Elizabeth Taylor!" 30-year-old reality star Kim Kardashian -- who posed as Taylor in a recent issue of Harper's Bazaar -- mourned. "She will always be my idol!"

Rose McGowan, 37, was equally shocked by the news of Taylor's passing. "I am devastated," she tweeted. "The Queen has died. Her talent, beauty, dedication to curing AIDS, love of love and her violet eyes will live on."

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"Rest in peace Elizabeth Taylor," Denise Richards, 40, tweeted. "Thoughts and prayers to your family and loved ones. You will be missed."

"Rest in peace, Elizabeth Taylor," mom-to-be Alyssa Milano, 38, tweeted. "You are a prism & will live on through all the good you did while you were with us."

"We have lost an amazing talent and beautiful soul!" Melissa Joan Hart, 34, added. "RIP Elizabeth Taylor."

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"A legendary woman has left us today," Kourtney Kardashian, 31, tweeted. "The world will not be the same without her beauty, glamour, generosity and gift of giving."

"National Velvet, Cleopatra, Who's Afraid of Virginaa Woolf: so many memories of a Hollywood icon. Happy she was with her family," Katie Couric, 54, told her followers. "Important point I omitted: she was an extraordinary humanitarian and did so much for aids awareness; perhaps her greatest legacy."

"OMG RIP Elizabeth Taylor!A woman who did HER at all times!" Taraji P. Henson, 40, tweeted. "Rest with the Angels!"

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"Such a sad day when a legend like Elizabeth Taylor passes away," Bethenny Frankel, 40, wrote. "Fitting that it's gloomy and rainy in New York. A place of sadness."

"RIP to the glamour goddess Elizabeth Taylor," Khloe Kardashian, 26, tweeted. "Thank you for sharing your life with us. Thank you for the memories."

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