Shannen Doherty
The Beverly Hills, 90210 alum, who has herself been battling cancer for years, wrote on Instagram, "I admire your strength thru the endless onslught you've been under while going through cancer."
Catherine Zeta-Jones
On March 22, 2024, Kensington Palace released a video of Kate Middleton revealing that she is undergoing treatment for cancer, which was discovered after she had abdominal surgery in January.
"Wales and the World is with you HRH Princess of Wales," Zeta-Jones, who was born in Wales and was made a Commander of the British Empire (CBE) by now-King Charles III in 2011, wrote on Instagram. "Love to you always."
Olivia Munn
The Newsroom alum, who revealed March 13 she has been battling breast cancer, commented on Kensington Palace's Instagram video of Kate, "Thank you for showing what it's like to fight with grace and determination for yourself and your family. Wishing you all the best."
Angie Harmon
"We are praying for your full & complete recovery & for strength of mind, body & spirit for you & your entire family," the Rizzoli & Isles alum commented on Kensington Palace's video of Kate. "Thank you for your beautiful spirit & courage."
Lauren Sánchez
The media personality, fiancée of Amazon founder Jeff Bezos, commented on the post as well, writing, "Sending love."
British Prime Minister Rishi Sunak
"My thoughts are with the Princess of Wales, Prince of Wales, the Royal Family and in particular her three children at this difficult time," he said in a statement on X. "The Princess of Wales has the love and support of the whole country as she continues her recovery. She has shown tremendous bravery with her statement today."
He added, "I know I speak for the whole country in wishing her a full and speedy recovery and look forward to seeing her back in action when she's ready."
White House Press Secretary Karine Jean-Pierre
Speaking at a press briefing following news of Kate's health battle, she said their thoughts are with the princess "and her family members and friends during this incredibly difficult time," adding, "certainly we wish her a full recovery."
James Middleton
"Over the years, we have climbed many mountains together," Kate's brother wrote on Instagram, alongside a childhood pic of the two, after she revealed her health diagnosis. "As a family, we will climb this one with you too."
Charles Spencer
The ninth Earl Spencer, brother of the late Princess Diana and Prince William and Prince Harry's uncle, wrote on Instagram, "Incredible poise and strength."
Meghan Markle & Prince Harry
The Duke and Duchess of Sussex, who stepped back as senior royals in 2020 and live in California, said in a statement to NBC News, "We wish health and healing for Kate and the family and hope they are able to do so privately and in peace."
King Charles III & Queen Camilla
A Buckingham Palace spokesperson said the King, who shared his own cancer diagnosis in February, is "so proud of Catherine for her courage in speaking as she did."
In fact, Charles has "remained in the closest contact with his beloved daughter-in-law throughout the past weeks," the rep told NBC News, adding that both he and Camilla "will continue to offer their love and support to the whole family through this difficult time."
U.S. First Lady Jill Biden
"You are brave," President Joe Biden's wife wrote on X, "and we love you."
Canadian Prime Minister Justin Trudeau
"On behalf of Canadians, I’m sending my support as she undergoes treatment," he wrote on X. "We’re all wishing her a swift recovery."