Beloved singer and actress Olivia Newton-John passed away at the age of 73 Monday, following a decades-long battle with breast cancer.

Fans arrived in droves to place flowers on her star on the Hollywood Walk of Fame and reminisce over the life of the Australian idol, who was also an activist for holistic and plant-based cancer treatment. An outpouring of remembrances came forth from fellow celebrities, including a particularly touching tribute from her long-time friend and colleague, John Travolta.

“My dearest Olivia, you made all of our lives so much better. 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! Your Danny, your John!” he said in an Instagram post.

The multi-talented pair became a global sensation after the release of the 1978 musical “Grease,” which went on to be the highest-grossing film of the year and an international sensation. Newton-John at first resisted taking the part because she felt she was too old for the role, but producer Allan Carr was able to convince her to take it on and the rest was history.