Kelly Preston, the actress and wife of John Travolta, has died aged 57.

Travolta posted on Instagram: "My beautiful wife Kelly has lost her two-year battle with breast cancer. She fought a courageous fight with the love and support of so many."

The couple had been married for nearly 29 years. Preston's career included roles in Twins, From Dusk Till Dawn, Jerry Maguire and The Cat in the Hat.

She also collaborated with her husband on Battlefield Earth and Old Dogs.

In his post, Travolta thanked the health workers who had looked after his wife "as well as her many friends and loved ones who have been by her side".

"I will be taking some time to be there for my children who have lost their mother, so forgive me in advance if you don't hear from us for a while. But please know that I will feel your outpouring of love in the weeks and months ahead as we heal. All my love, JT".

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It is with a very heavy heart that I inform you that my beautiful wife Kelly has lost her two-year battle with breast cancer. She fought a courageous fight with the love and support of so many. My family and I will forever be grateful to her doctors and nurses at MD Anderson Cancer Center, all the medical centers that have helped, as well as her many friends and loved ones who have been by her side. Kelly’s love and life will always be remembered. I will be taking some time to be there for my children who have lost their mother, so forgive me in advance if you don’t hear from us for a while. But please know that I will feel your outpouring of love in the weeks and months ahead as we heal. All my love, JT

A post shared by John Travolta (@johntravolta) on Jul 12, 2020 at 10:20pm PDT

The couple's son Jett Travolta died at the age of 16 in January 2009 from a seizure during a family holiday in the Bahamas.

They have two other children, Ella Bleu and Benjamin.

Ella wrote on Instagram: "I have never met anyone as courageous, strong, beautiful and loving as you."

A family representative told People magazine that she died on Sunday morning and that she had kept her cancer diagnosis private.

"She had been undergoing medical treatment for some time, supported by her closest family and friends," the family representative said.

"She was a bright, beautiful and loving soul who cared deeply about others and who brought life to everything she touched. Her family asks for your understanding of their need for privacy at this time."

Born Kelly Kamalelehua Smith in Honolulu, she changed her name to Kelly Preston before securing her first film role in the 1985 romcom Mischief, then appeared in another teen comedy, Secret Admirer.

Russell Crowe was among the Hollywood stars paying tribute, remembering Preston as "a lovely person" and a "sparkly eyed gem".

Kelly Preston.
Can’t remember where, but, met first in late ‘92 I think.
Such a lovely person. In 1995 we auditioned together for Breaking Up, Salma Hayek got that gig.
I havent seen her much, but when I did, she was always the same sparkly eyed gem.
Love to her family.
R.I.P

— Russell Crowe (@russellcrowe) July 13, 2020

Singer Mariah Carey also responded to Travolta's post, saying she was "sending so much love to you and your family in this heartbreaking moment".

Other tributes came from Maria Shriver and Josh Gad, who said he was "in absolute shock".

Shocked by this sad news. Kelly was such a bright loving soul, a talented actress, and a loving mom and wife. My heart breaks for her family who have already known such sadness and grief. Join me in sending them love and strength. #RIP #KellyPreston https://t.co/DndcfOtlOn

— Maria Shriver (@mariashriver) July 13, 2020

I’m in absolute shock. What a beautiful and amazing actress and person. So sad to hear of her passing at such a young age. My heart goes out to John Travolta and the entire family. What a loss. 🙏 RIP #KellyPreston https://t.co/yRqOmI3CjW

— Josh Gad (@joshgad) July 13, 2020

Spencer Breslin, who played Preston's character's son in The Cat in the Hat, remembered his "screen mom" as being "a lovely woman", adding: "Such a sad loss."

Alec Baldwin, who also appeared in that 2003 film, said Preston was "one of the loveliest people I've ever worked with".

How tragic and sad about Kelly Preston. I shot CAT IN THE HAT with Kelly many years ago .
She remains one of the loveliest people I’ve ever worked with. Funny. Kind.
My heart goes out to John and their family.

— HABFoundation (@ABFalecbaldwin) July 13, 2020

Lost star Daniel Dae Kim, meanwhile, said he had been "lucky enough to work with her on one of my very first films", 1999's For Love of The Game.

"We were shooting on cold days in Colorado, but she couldn't have been warmer or kinder to a young, nervous actor trying to make good," he continued.

'Keep creating love'

One of Preston's last screen roles was in the 2018 crime biopic Gotti, in which she appeared opposite her husband.

While promoting the film at the Cannes Film Festival, the actress spoke to reporters about their long relationship.

"We took the time to get to know each other," she said. "Marriage doesn't just happen on its own, you have to keep creating love.

"We also keep it light. Neither of us like to fight so we purposely do not push each other's buttons."