Shortly after news of Newton-John's death broke on Monday, Travolta posted a sweet tribute to her on his Instagram. "My dearest Olivia, you made all of our lives so much better," Travolta captioned a photo of the actress. "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!"
Travolta ended his tribute with, "Your Danny, your John!"
Earlier on Monday, it was announced that Newton-John, the English-Australian singer and actress best known for her iconic portrayal of Sandy in Grease, died at age 73. According to her official social media pages, she died on Aug. 8 while at her home in Southern California. A statement said, "Dame Olivia Newton-John (73) 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." The announcement did not cite her cause of death but did note her 30-year battle against breast cancer.
Travolta and Newton-John, who starred together in Grease in 1978, reunited to reprise their characters, Danny and Sandy, in a nostalgic dress-up moment for a special "Meet n' Grease" sing-along event in West Palm Beach, Fla. Newton-John shared a photo of the moment from backstage. "First time in costume since we made the movie ! So excited!!" she captioned the post.
Paramount Pictures/Fotos International/Getty Images Olivia Newton-John and John Travolta as Sandy and Danny in 'Grease'
Taking a page out of Sandy's book, Newton-John made a costume change later in the night, swapping out the "good girl" look for her original leather jacket for a Q&A with Travolta. The two actors also joined fans in singing along "Hopelessly Devoted to You," "Sandy," and "Greased Lightning."
See Travolta's full tribute below: