Leonardo DiCaprio, Jane Fonda and More Pay Tribute to Jane Goodall

Stars are mourning the loss of legendary conservationist Dr. Jane Goodall.

The 91-year-old animal welfare advocate died of natural causes in California during a speaking tour, her namesake institute announced in a statement on Wednesday, Oct. 1.

“Dr. Goodall’s discoveries as an ethologist revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world,” they wrote in a tribute.

Known globally for a 65-year study on wild chimpanzees in Gombe, Tanzania, Goodall penned more than 27 books throughout her lifetime and completed a doctoral thesis titledThe Behaviour of Free-living Chimpanzees in the Gombe Stream Reserve in 1965 without an undergraduate degree, according to a memorial page from her institute.

Following the news of her death, a slate of celebrities, politicians and organizations from around the world have mourned her loss online.

“Today we have lost a true hero for the planet, an inspiration to millions, and a dear friend,” actor and environmental activist Leonardo DiCaprio wrote in a lengthy Instagram tribute.

“For decades, Jane traveled the world with tireless energy, awakening generations to the wonder of the natural world. She spoke directly to the next generation, instilling hope, responsibility, and the belief that every individual can make a difference. She inspired millions to care, to act, and to hope. She never stopped,” he continued. “My deepest condolences to her family. Please join me in honoring her legacy by supporting @janegoodallinst and other conservation groups which she cared about.”

He added, “My last message to Jane was simple: ‘You are my hero.’ Now, we all must carry the torch for her in protecting our one shared home.”

In a separate tribute, Jane Fonda said that her “heart breaks at the news.”

“Through her work with chimps, she did more than any human being has, to let us understand the richness of animal lives: their intelligence, skills, unique personalities, use of tools, empathy, suffering when one of theirs was killed,” the star wrote. “I loved her very much. I think the best way we can honor her life is to treat the earth and all its beings like our family, with love and respect.”

Added Michael Douglas, “RIP to my fellow UN Messenger of Peace, Dr. Jane Goodall. Her legacy will forever be remembered for her unwavering dedication to our planet.”

Sharing a carousel of photos of Goodall, longtime morning news anchor Al Roker remembered heras a “gentle soul but a fierce champion, while in a separate post, Julia Louis-Dreyfus, who once hosted the legendary conservationist on her Wiser Than Me podcast, said she was “so blessed and so grateful to have crossed paths with this wise giant.”

“Jane Goodall was a legendary figure and a friend. I admired her, learned from her, and was so honored to get to spend time with her over the years,” wrote Maria Shriver on Instagram. In 2009, Goodall became a recipient of Shriver’s Minerva Award, honoring women “who serve on the front-lines of humanity.” 

“She stayed at her mission and on her mission. She changed the world and the lives of everyone she impacted. The world lost one of its best today, and I lost someone I adored,” Shriver added.

Former daytime host Ellen DeGeneres shared a clip of when Goodall appeared on the show in honor of her 85th birthday.

During the television appearance, Goodall recalled how few opportunities there were for women to become scientists while she was growing up, yet her mother offered simple advice: “If you really want this, you’ll have to work really hard, take advantage of all opportunities, but don’t give up.”

Another former host, Rosie O’Donnell mourned Goodall shortly after her death was announced publicly, writing on Instagram, “Angel on earth- rip jane.”

Meanwhile, former Canadian Prime Minister Justin Trudeau called her a “pioneer whose research and advocacy reshaped our understanding of the natural world.”

Added Hilary Clinton, “I’ll so miss her courage and commitment to help expand what we know about our world and preserve it for the generations to come.”

The United Nations also honored Goodall, who served as a Messenger of Peace for the organization since 2002, focusing on conservation and environmental issues.

“Today, the UN family mourns the loss of Dr. Jane Goodall,” the group wrote online, noting the scientist, “worked tirelessly for our planet and all its inhabitants, leaving an extraordinary legacy for humanity and nature.”

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PBS’ Nature confirms to PEOPLE on Wednesday, Oct. 1 that the program is planning to air a two-hour documentary in 2026 called Matriarch, focusing on Goodall and her efforts in Gombe, Tanzania.

“In the early 1960s, as a young woman, she entered the African forest to study chimps with absolutely no background in animal behavior, rather, equipped only with a keen sense of observation and a love and curiosity about animals,” says Nature Executive Producer Fred Kaufman.

“Her long-term study of these primates has fundamentally changed how we view them, from their use of tools to their displays of emotion,” Kaufman continues. “Her contribution to understanding wild animals is nearly unmatched.”