He had been suffering from dementia for several years
Malcolm Young, who co-founded the hard rock band AC/DC with his younger brother, has died aged 64.
The guitarist - described as a "visionary, a perfectionist and a unique man" - had been suffering from dementia for several years.
In a statement, AC/DC said: "Today it is with deep heartfelt sadness that AC/DC has to announce the passing of Malcolm Young.
"Malcolm, along with Angus, was the founder and creator of AC/DC.
"With enormous dedication and commitment he was the driving force behind the band.
"As a guitarist, songwriter and visionary he was a perfectionist and a unique man. He always stuck to his guns and did and said exactly what he wanted.
"He took great pride in all that he endeavored. His loyalty to the fans was unsurpassed."
Angus Young, Malcolm's brother and fellow AC/DC co-founder, added: "It is hard to express in words what he has meant to me during my life, the bond we had was unique and very special.
"He leaves behind an enormous legacy that will live on forever.
"Malcolm, job well done."
He is survived by his wife O'Linda, children Cara and Ross, son-in-law Josh, three grandchildren, sister and brother.
The family will open a memorial page next week for messages of condolence and asked people to donate to The Salvation Army instead of sending flowers.
Born in Scotland, Young and his family moved to Australia when he was 10 and he grew up in Sydney.
Young founded the band with his brother in 1973 until he took retirement in 2014, due to health reasons. He was absent briefly during 1988.
The group was inducted into the Rock and Roll Hall of Fame in 2003.
AC/DC recorded 17 studio albums and are perhaps best known for Highway To Hell, Back In Black and For Those About To Rock (We Salute You), released in the late 1970s and early 1980s.