John Travolta pens sweet tribute to 'Grease' costar Olivia Newton-John in the wake of her death: 'I love you so much'

• John Travolta honored "Grease" costar Olivia Newton-John following her death at 73 years old.
• "You made all of our lives so much better," he wrote in an Instagram post shared on Monday.

John Travolta called Olivia Newton-John's impact "incredible" in the wake of her death on Monday.

The singer and "Grease" actress died at the age of 73 after a decades-long battle with metastatic breast cancer.

"My dearest Olivia, you made all of our lives so much better. Your impact was incredible," Travolta wrote on Instagram, alongside an old photo of Newton-John.

"I love you so much. We will see you down the road and we will all be together again. Yours from the moment I saw you and forever!"

He signed the post: "Your Danny, your John!"

Newton-John and Travolta met through their roles as Sandy Olsson and Danny Zuko in the hit musical "Grease," released in theaters in 1978.

The two played love interests who met at a beach over the summer and continued their romance at Rydell High.

Newton-John was nominated for a Golden Globe for best performance by an actress in a motion picture comedy or musical for her role in "Grease."

Newton-John's portrayal of Sandy is the role most associated with her, though she appeared in various other shows and films. She also reunited with Travolta for the 1983 movie "Two of a Kind." The two collaborated on the song "Take a Chance" as part of the film's soundtrack.

Newton-John was also an accomplished musician, having earned four Grammys and 12 total nominations in her lifetime.

She was already a Grammy winner when she starred in "Grease," after winning her first award in 1973. She earned two more awards the following year. In 1982, Newton-John won the Grammy for video of the year for "Physical."

In the years after "Grease," the singer released more than 10 albums, some of which were Christmas records. She and Travolta released a joint holiday album in 2012 titled "This Christmas."

To celebrate the 40th anniversary of "Grease" in 2018, the costars appeared together at a screening of the movie.

The following year, Newton-John and Travolta participated in a "Grease" sing-along event and Q&A in Florida. They even wore outfits similar to those of their musical characters.

Newton-John was diagnosed with breast cancer in 1992 and said that her treatment lasted for almost one year. Her cancer returned in 2013, but the actress didn't reveal the news publicly. Four years later, Newton-John said that her breast cancer returned and it metastasized to her lower back.

In 2020 at a G'Day USA event in Beverly Hills, she told reporters that she was "winning over it well" and "getting stronger and better all the time."

In 2021, Newton-John told "Today" show host Hoda Kotb that she was still living with cancer, but cannabis was a "huge part of my healing."

Outside of her music and acting careers, she was appointed Officer of the Order of the British Empire (OBE) in 1979 and became Dame Commander of the Order of the British Empire (DBE) in 2020 for her work in the fields of entertainment, charities, and cancer research.