Oddball the maremma, one of Australia's most iconic pooches, has died aged 15 in south-west Victoria.
Her pioneering role as Middle Island's penguin protector gained international acclaim and inspired the movie Oddball starring Shane Jacobson.
Her owner, Allan 'Swampy' Marsh said Oddball's pioneering role in protecting her penguin pals was "a bit of a cameo".
In fact, she only spent three weeks of her life on the island before succumbing to loneliness and swimming to shore.
Mr Marsh said his "right-hand lady" had passed away peacefully in Warrnambool of old age.
"She was 105 in dog years, so she had a pretty good innings," he laughed.
"She's had a great legacy, and she'll always be remembered as one of the most polite dogs around."
Penguin pals 'indebted'
When the Middle Island Maremma Project began in 2006, Warrnambool had seen a sharp decline in its little penguin colony due to fox predation.
Maremma dogs were trained and placed on the island to protect the birds from predators like foxes during breeding seasons.
Despite Oddball's unexpected return from the island, Mr Marsh said it sparked the idea of dogs protecting penguins and got the program running.
"We trained up a bunch of other dogs who were a little bit less emotional, and the rest is history," he said.
"We haven't had a fox on the island since."
Community mourns popular dog
Oddball's death has rocked the coastal community with the local council mooting plans to immortalise her in a statue opposite Middle Island.
"It's sad, but it's a little bit momentous too," Warrnambool City Council mayor Kylie Gaston said.
"It would be great to have a statue to remember her by, but also a point of focus for tourists, like Red Dog."