Dame Olivia Newton-John, British-born Australian singer and star of hit musical Grease, has died following a prosperous career and decades of charity work.
Messages posted to her official social media accounts said the 73-year-old "passed away peacefully" at her ranch in southern California surrounded by family and friends.
She won multiple Grammy awards over a five-decade-long career and was well known for her role as Sandy in the film Grease.
On her official Facebook page, husband John Easterling described Newton-John as 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," he wrote.
The entertainer is survived by her husband John Easterling and daughter Chloe Lattanzi.
Newton-John had early success through the song Let Me Be There, which won her a Grammy.
Her most famous records included the Record of the Year Grammy winner I Honestly Love You and Physical.
However, Newton-John's career soared after she starred in the film adaptation of the Broadway musical Grease as Sandy alongside John Travolta in 1978.
The soundtrack would spend 12 non-consecutive weeks at number 1, with Newton-John becoming the second woman to have two singles – Hopelessly Devoted to You and Summer Nights – in the Billboard top-five simultaneously.
The fast-stepping Travolta-Newton-John duet You're the One That I Want was one of the era's biggest songs and has sold more than 15 million copies.
Grease co-star John Travolta posted a tribute to Newton-John on social media.
"My dearest Olivia, you made all of our lives so much better," Travolta said.
"Your impact was incredible. 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!"
Her daughter, who is also a singer and actress, posted a series of images to social media as a tribute to her mother.
Three days earlier, Lattanzi had posted an old photo of the two of them with the caption: "I worship this woman. My mother. My best friend."
From 1973-83, Newton-John was among the world's most popular entertainers.
Physical, the bouncy, R-rated smash released in 1981, was Number 1 for 10 weeks and was named Billboard's song of the year despite being banned by some radio stations.
An aerobics-friendly promotional clip, filmed in the early years of MTV, won a Grammy for best video.
Private life and charity
She had a few hits after Physical, but her career declined and Newton-John became more likely to make the news because of her private life.
In 1992, as she was preparing a concert tour, her father died and she was diagnosed with breast cancer.
Her marriage to actor Matt Lattanzi, with whom she had a daughter, actor-singer Chloe Lattanzi, broke up in 1995 and a years-long relationship with cameraman Patrick McDermott ended mysteriously when he went missing on a fishing trip in 2005.
"He was lost at sea, and nobody really knows what happened," Newton-John told Nine's 60 Minutes in 2016.
"It's human to wonder. But you know, those are the things in life you have to accept and let go. Because whenever you go through difficult times, there's always those concerns."
Newton-John's recent albums included Stronger Than Before, a collaboration with Travolta, This Christmas and the autobiographical Gaia: One Woman's Journey.
The latter was inspired by her cancer diagnosis and by the loss of her father.
Newton-John married John Easterling, founder of the Amazon Herb Company, in 2008.
She was involved in numerous charitable causes, serving as a goodwill ambassador for the United Nations Environment Programme.
Newton-John, whose sister died of brain cancer, became an advocate after her first bout with breast cancer and she established the Olivia Newton-John Cancer Wellness and Research Centre in her hometown of Melbourne.
She also marketed what was known as the Olivia Breast Self-Exam Kit.
Newton-John was the daughter of German literature professor Brin Newton-John and Irene Born, whose father was Nobel Prize-winning physicist Max Born.
The family moved to Australia when Olivia was five, but she returned to England in her teens and lived with her mother after her parents broke up.
She had early dreams of becoming a veterinarian but was winning singing contests in high school and before age 20 had toured army bases and clubs and recorded her first single, Till You Say You'll Be Mine.
Olivia Newton-John was made a dame in the Queen's New Year honours list in 2019.
She received the honour for her services to charity, cancer research and entertainment.
At the time Newton-John said: "I am extremely excited, honoured and grateful beyond words to be included with such an esteemed group of women who have received this distinguished award before me.
"As a girl born in Cambridge, I am very proud of my British ancestry and so appreciative to be recognised in this way by the United Kingdom."
When Newton-John beat out Dolly Parton and Loretta Lynn for the Country Music Association's top artist of 1973, Tammy Wynette helped founded the Association of Country Entertainers, a club designed to exclude Newton-John and other crossover performers.
In 1974, Newton-John represented the United Kingdom in the Eurovision Song Contest with the song Long Live Love where she finished fourth behind ABBA's winning Swedish entry Waterloo.
But Newton-John had a show business admirer who with her became one of movies' most unforgettable teams.
Travolta had starred in the stage version of Grease and for the planned film thought Newton-John would be the "ultimate" Sandy, the nice girl who gets tough in the final act and gets her man.
"I worried that at 29 I was too old to play a high school girl," Newton-John told The Telegraph in 2017.
"Everything about making the film was fun, but if I had to pick a favourite moment, it was the transformation from what I call Sandy 1 to Sandy 2.
"I got to play a different character and wear different clothes, and when I put on that tight black outfit to sing 'You're the One That I Want,' I got a very different reaction from the guys on the set."
In the film, set in the 1950s, Newton-John's prim Sandy has a summer fling with Danny, the "greaser" portrayed by Travolta, but the relationship falls apart because of their cultural differences.
In the end they reconcile as their roles reverse, with Danny cleaning up his act and Sandy making a striking appearance in a tight black leather outfit.
Acting Prime Minister Richard Marles told the ABC it was a "really sad day for Australia".
"I think for people of my generation who grew up with Grease … it's one of these moments when you feel like an era has come to an end, and the world is a little emptier," he said.
"But, we all grew up watching Olivia Newton-John, and it's hard to imagine that she's no longer with us."
Opposition Leader Peter Dutton described Newton-John as "so much more than a star".
"She was a trailblazer of achievement, talent, and decency," he said.
"Hers was a career of enormous achievement — on stage, on screen, and in advocacy for good causes.
"On behalf of the federal coalition, Kirilly and I extend our condolences to Olivia's family, friends, and her legion of fans — here in Australia and right around the world."
ABC/wires
