Veteran ABC journalist and broadcaster Mark Colvin has died at the age of 65.
Colvin was the presenter of the ABC's flagship radio program PM from 1997.
The award-winning reporter has been battling a rare and chronic autoimmune disease, Wegeners Granulomatosis, which he contracted in Rwanda while covering the troubled nation's genocide in 1994.
In 2012, he received a kidney transplant and allowed the procedure to be filmed for television.
Colvin has been a strong advocate for organ donations, with many people on social media paying tribute by calling on the public to register as an organ donor.
He is survived by his wife Michele McKenzie, who he married in 1987, two sons and grandchildren.
ABC Managing Director Michelle Guthrie said the public broadcaster will "miss him enormously, and extend our thoughts to his family and friends".
"For many Australians, Mark's steady and measured voice as host of PM brought them the essential news of the day and kept them informed about events of national and international importance," she said in a statement.
Colvin had worked at the ABC for more than forty years, having joined the broadcaster as a cadet in February 1974.
Just last year, he released a book titled 'Light and Shadow' about his work as a foreign correspondent covering some of the most dangerous flashpoints of recent history, including the end of the Cold War, the Tehran hostage crisis and the build up to the First Gulf War in Iraq.
His autobiographical book also details what it was like as a young man finding out that his diplomat father was really an MI6 spy.
Colvin, who was a well known music buff, also released a Spotify playlist of tunes, which he described as a "soundtrack" to accompany the book, featuring music greats The Beatles, Bob Dylan and Van Morrison.
Messages of tribute and support for his family and friends have poured out from the media sphere and beyond following the announcement of his death.
The ABC's Director of News Gavin Morris said Colvin's passing left "an unfillable void".
"Mark was one of Australia's finest journalists," Morris said in a statement.
"He was an important part of the ABC community as a mentor and teacher to young reporters and as a voice of wisdom and experience to many older ones.
"Our reporters and producers felt strengthened by his presence in the newsroom and emboldened by the sound of his voice on our airwaves."
Opposition Leader Bill Shorten said Colvin was "a gentleman of journalism", while Prime Minister Malcolm Turnbull described his work as "elegant and erudite".
"In a world of superficiality, he was always informed and honest. We've lost a good man," Turnbull tweeted on Thursday afternoon.
Sydney Morning Herald investigative journalist Kate McClymont described him as "one of the giants of our profession".
ABC political journalist and commentator Julia Baird said Colvin possessed "a rare dignity" and "a deep love of his craft".
Host of the ABC program Home Delivery, Julia Zemiro, described Colvin's "curiosity" and "deep love and knowledge of music".
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