Little Oak Sanctuary, which has been looking after Chris since 2015, announced his death on social media on Tuesday morning.

"We are heartbroken at the loss of this sweet, wise, friendly soul," the sanctuary wrote on Facebook.

Chris shot to fame in 2015 after he was discovered roaming Mulligans Flat, after being on the loose for six years.

He underwent a life-saving shearing operation to get rid of his woolly coat, after being rescued by members of the RSPCA ACT.

Australian Shearer Hall-of-Famer Ian Elkins helped to shear Chris at the time. It ended up breaking the world record for the heaviest sheep fleece.

The Guinness Book of Records confirmed the record in late 2015; 41.1 kilograms of fleece was shorn off Chris.

Chris' story went viral, with articles appearing in The Washington Post, CNN, the BBC and CBS.

Little Oak vice president and co-founder Kate Luke said Chris died on Tuesday morning of natural causes.

"He's been really happy and healthy recently. His death came out of the blue. His system just gave way," she said.

"He was coming up to 10 years, and generally sheep can live up to 12 years old.

"We found Chris on Tuesday morning when he didn't show up to get breakfast."

Ms Luke said Chris had been stand-offish at first after arriving at the sanctuary, having had minimal human contact for the first few years of his life.

However, he soon warmed to staff and visitors, quickly becoming a favourite of guests.

"Gradually he became more confident and up the front of the group, he would always go for head scratches," Ms Luke said.

"He was a sanctuary favourite and he had a deep baritone noise and was always one of the first to arrive for food."

Little Oak Sanctuary said Chris's death was being felt by everyone at the farm.

"Chris is known as the world-record holder for having grown the heaviest fleece on record. He was so much more than this, so very much more," the sanctuary said. on Facebook.

"We will remember him for all that he was - someone, not something - here with us, not for us."

A book for children telling the story of Chris has also been written by the RSPCA, with funds raised from its sale going towards the animal rescue organisation.

Chris' record-breaking fleece has also been on display at the National Museum of Australia for several years.

Senior curator, Dr Martha Sear, said the fleece was one of the museum's most popular exhibits.

"It's important to note that the two most sought-after objects at the museum are Phar Lap's heart and Chris' fleece," she said.

"There's that place that animals hold in our national affection that is important, and I expect we'll see visitors come through over the new few weeks to pay their respects to Chris."

The museum acquired the fleece in 2016, and after it underwent preservation treatment, the woolly coat has taken pride of place in the museum's Landmarks exhibition.

"The fleece captured people's imagination globally, and that added significance to the fleece, and there was a story that connected with people around the globe," Dr Sear said.

"Chris left an imprint on me as he has on others, and his story touches your heart."