Lucky Diamond died Tuesday, in her dog bed at her New York City home. The rescued Maltese was about 15 years old, according to her owner, Wendy Diamond.
Diamond dedicated her life to animal welfare after adopting Lucky in 1999.
The sweet-but-spunky canine patiently starred in photo ops with celebrities ranging from Kristen Stewart of "Twilight" fame to hip-hop star Snoop Dogg and actress Betty White, who is herself an animal-welfare advocate.
In November, the Guinness Book of World Records announced that Lucky was "the animal photographed with the most famous people." Her total at the time was 363, including Kim Kardashian, Richard Branson "and many more," Guinness confirmed Tuesday.
Lucky also was involved in widespread charity work. Among other things, her fuzzy, doe-eyed lovability resulted in funds and awareness for the Humane Society of New York. Her last public appearance was as "chair dog" of the American Cancer Society's "Bark for Life" on May 6 in Manhattan's Riverside Park.
Diamond and Lucky visited Russia, Greece and Mexico while advocating for animals. Fans worldwide followed their adventures and posted supportive Facebook messages after Lucky's February diagnosis of spleen cancer.
"She made me realize how lucky I am, no matter what transpired in my life," said Diamond. "I'm beyond grateful for the outpouring of generosity and support from friends and strangers who know exactly how much Lucky meant to me."
With inspiration from Lucky, Diamond wrote the forward to the book "Chicken Soup for the Soul: What I Learned from the Dog."
On July 12, the always-game Lucky was to be dressed as a bride for an over-the-top, luxury "wedding" extravaganza benefiting the Humane Society. Diamond, who did not shy away from references to Lucky's dwindling time on earth, has decided to adopt another lucky dog so that the show -- and the cause -- can go on. The winner of a contest to choose the canine "groom" will be named on June 28.
"Lucky's life and her legacy of saving the underdog will be celebrated and her mission continued," Diamond said.