AC/DC co-founder and guitarist Malcolm Young has died after battling dementia for several years. He was 64.
He died at home with his family at his bedside, the band said in a statement posted on the their website.
"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 endeavoured. His loyalty to the fans was unsurpassed. As his brother 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," the band said.
Young played rhythm guitar to Angus' lead, and his driving riffs and mop-top hair were signatures of the band's sound and image for decades.
Angus Young, in a separate statement added that Malcolm took "great pride in all that he endeavoured."
AC/DC was inducted in 2003 into the Rock & Roll Hall of Fame, which described its sound as "scorched-earth, metallic hard rock which has rarely deviated from a template of head- banging-inducing guitar riffs, flashy drums and banshee-yell vocals."
The band is also one of the best-selling in music history, according to the Recording Industry Association of America, having sold more than 70 million albums in the US. The band's original lead singer, Bon Scott, died in 1980. He was replaced by Brian Johnson.
Three years ago the band announced Young was stepping down to receive treatment for dementia. Shortly afterwards he retired permanently, to be replaced by one of his nephews, Stevie, for the band's most recent tour.
Young's fellow musicians, as well as rock n' roll fans, paid their tributes on Twitter.
"RIP Malcolm Young," wrote singer-songwriter Ryan Adams. "He was the founding member of AC/DC & the engine that roared behind the most powerful band in the world." Guitarist Eddie Van Halen said "it is a sad day in rock and roll."
Paul Stanley wrote, "The driving engine of AC/DC has died. A tragic end for a sometimes unsung icon. One of the true greats. RIP."
Ozzy Osbourne tweeted, "So sad to learn of the passing of yet another friend, Malcolm Young. He will be sadly missed. God Bless @ACDC"
"The greatest rhythm guitar player ever and a songwriter beyond compare. Malcolm Young is forever a legend," Greg Dulli said.
Bryan Adams wrote, "RIP Malcolm Young. Your guitar playing was a huge inspiration. Thanks for that."
AC/DC plans to create a memorial website at which fans can send messages to Malcolm Young's survivors, including his wife, O'Linda; children, Cara and Ross; son-in-law, Josh; three grandchildren; and his sister and brother. The family asked that in lieu of flowers, fans donate to The Salvation Army.