Dame Olivia Newton-John (26 September 1948 – 8 August 2022) was a British and Australian singer and actress. With over 100 million records sold, Newton-John was one of the best-selling music artists of all time, as well as the highest-selling female Australian recording artist of all-time.

In 1978, Newton-John starred in the musical film Grease, which was the highest-grossing musical film at the time and whose soundtrack remains one of the world's best-selling albums. It features two major hit duets with co-star John Travolta: "You're the One That I Want"—which is one of the best-selling singles of all time—and "Summer Nights". Her signature solo recordings include the Record of the Year Grammy winner "I Honestly Love You" (1974) and "Physical" (1981)—Billboard's highest-ranking Hot 100 single of the 1980s. Other defining hit singles include "If Not for You" and "Banks of the Ohio" (both 1971), "Let Me Be There" (1973), "If You Love Me (Let Me Know)" (1974), "Have You Never Been Mellow" (1975), "Sam" (1977), "Hopelessly Devoted to You" (1978; also from Grease), "A Little More Love" (1978), "Twist of Fate" (1983) and, from the 1980 film Xanadu, "Magic" and "Xanadu" (with the Electric Light Orchestra).

Newton-John's accolades include four Grammy Awards, a Daytime Emmy Award, nine Billboard Music Awards, six American Music Awards and a star on the Hollywood Walk of Fame. She scored fifteen top-ten singles, including five number-one singles on the Billboard Hot 100, and two number-one albums on the Billboard 200: If You Love Me, Let Me Know (1974) and Have You Never Been Mellow (1975). Eleven of her singles (including two Platinum) and fourteen of her albums (including two Platinum and four 2× Platinum) have been certified Gold by the Recording Industry Association of America (RIAA). She was appointed Officer of the Order of Australia in 2006 and Dame Commander of the Order of the British Empire in 2020.

Newton-John, who had breast cancer three times, was an advocate and sponsor for breast cancer research. In 2012, the Olivia Newton-John Cancer & Wellness Centre at the Austin Hospital opened in her home town of Melbourne; in 2015, the facility was rechristened the Olivia Newton-John Cancer Wellness & Research Centre. She was also an activist for environmental and animal rights causes.