Olivia Newton-John, the British-born star of Grease, has died at the age of 73 after a long battle with breast cancer.
The actress and singer, who moved to Australia as a child, died "peacefully" at her ranch in southern California on Monday morning, surrounded by family and friends.
She was best known for her 1978 role playing Sandy in Grease, starring opposite John Travolta.
Her voice and beauty helped turn her into one of the biggest stars of the seventies, and she is credited with selling more than 100 million records over the course of a five-decade career.
The Grammy-winning superstar's best-known hits included "Physical" and "You're the One That I Want".
She had a few hits after "Physical," but her career declined and Newton-John became more likely to make news because of her private life.
In more recent years, Newton-John became best known as an advocate for breast cancer survivors.
She was first diagnosed with breast cancer in 1992, but it went into remission for numerous years. It later came back in 2013, followed by a third time in 2017.
Commenting on her illness in 2019, she said: "You can be a victim, or you can be a winner and enjoy your life."
In 2020, she was awarded a damehood from the Queen for her dedication to charity work and cancer research, as well as her success in entertainment.
Following her death, Newton-John widower, John Easterling, said: "Dame Olivia Newton-John passed away peacefully at her ranch in southern California this morning, surrounded by family and friends. We ask that everyone please respect the family's privacy during this very difficult time.
"Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer.
"Her healing inspiration and pioneering experience with plant medicine continues with the Olivia Newton-John Foundation Fund, dedicated to researching plant medicine and cancer."
Newton-John was born in Cambridge, but her family later emigrated to Australia, where her father Brin worked as the master of Ormond College at the University of Melbourne.
He had earlier served as an MI5 officer on the Enigma project at Bletchley Park, and took Rudolf Hess into custody during the Second World War.
Newton-John returned to the UK as a teenager to pursue a singing career and starred in the Eurovision song contest in 1974.
Her big break in Grease came four years later. She famously resisted the part, at first turning down producer Alan Carr because, she told The Telegraph, she thought she was too old for the role of a high school teen at the age of 27.
She is survived by her daughter Chloe Rose, 36, who posted a tribute to her mother on Instagram three days ago. "I worship this woman. My mother. My best friend," the actor-singer wrote.
'You made all of our lives better'
The entertainment world is mourning the loss of the beloved star, who has been hailed as "angelic voice" who produced "stone cold classic" songs.
In a heartfelt tribute on Instagram, her Grease co-star John Travolta said she made "all of our lives so much better".
"Your impact was incredible," he said.
"I love you so much. We will see you down the road and we will all be together again. Yours from the first moment I saw you and forever! Your Danny, your John!"
Australia's Prime Minister Anthony Albanese also paid tribute to Newton-John, calling her a "joyful glow in our lives".
"Her legacy will live on, in her music, her films and her determination that one day we will find a cure for cancer," Mr Albanese said on Twitter.
Singer Dionne Warwick, who recorded a duet with Newton-John in 2006, said she was one of the nicest people she had worked with and a "dear friend".
"Another angelic voice has been added to the Heavenly Choir," Warwick said on Twitter.
"Not only was Olivia a dear friend, but one of the nicest people I had the pleasure of recording and performing with. I will most definitely miss her.
"She now Rests in the Arms of the Heavenly Father."
Another angelic voice has been added to the Heavenly Choir. Not only was Olivia a dear friend, but one of the nicest people I had the pleasure of recording and performing with. I will most definitely miss her. She now Rests in the Arms of the Heavenly Father 🥲🙏🏾♥️
— Dionne Warwick (@dionnewarwick) August 8, 2022
Oscar-winning actress Marlee Matlin described Newton-John as the "sweetest and brightest light" as she recalled starring alongside her in the 1996 film It's My Party.
"I am so saddened at the news of the passing of Olivia Newton John," she said on Twitter.
"I remember being so star struck when I met her at my first Hollywood gathering for Paramount.
"She was the sweetest and brightest light and I loved getting to know her on It's My Party. RIP dear, sweet Olivia."
I am SO saddened at the news of the passing of Olivia Newton John. I remember being so star struck when I met her at my first Hollywood gathering for Paramount. She was the sweetest and brightest light and I loved getting to know her on 'It's My Party.' RIP dear, sweet Olivia. pic.twitter.com/4FFgolVQNk
— Marlee Matlin (@MarleeMatlin) August 8, 2022
US singer Richard Marx, who duetted with Newton-John, said his heart was "broken" and he would "miss her every day".
"My heart is broken. Rest now, sweet friend," he said on Twitter.
"You were as kind and loving a person as there's ever been. I'll miss you every day."