John Travolta says his wife Kelly Preston has died from breast cancer.
The actor wrote on Instagram: "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."
The actress, 57, had chosen to keep her diagnosis private.
A family representative told People.com that she died on Sunday morning and "had been undergoing medical treatment for some time, supported by her closest family and friends".
Preston appeared alongside Tom Cruise as his fiancee in Jerry Maguire, and with Arnold Schwarzenegger and Danny DeVito in the comedy Twins.
She also starred several times with her husband, most recently in mob flick Gotti in 2018.
The couple were married for more than 28 years, tying the knot at a midnight ceremony in Paris while Preston was pregnant with their first child Jett.
They had two more children - a daughter, who's now 20, and a nine-year-old son.
Jett Travolta died in 2009, aged 16, after suffering a seizure on holiday in The Bahamas.
Preston's last post on Instagram was in June, when she shared a picture of her family alongside the caption: "Happy Father's Day to the best one I know, we love you."
Travolta said he would be "taking some time to be there for my children", adding: "Please know that I will feel your outpouring of love in the weeks and months ahead as we heal."
Their daughter, Ella Blue, posted on Instagram: "I have never met anyone as courageous, strong, beautiful and loving as you."
Among others to pay tribute was Russell Crowe, who called her "such a lovely person".
The Gladiator star tweeted: "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."
Arnold Schwarzenegger's ex-wife, Maria Shriver, posted: "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."