Legendary US musician Lou Reed, whose band the Velvet Underground became one of the most influential in rock, has died aged 71.
The singer-songwriter's best-known hits included Perfect Day and Walk On The Wild Side.
Reed died on Sunday at the Long Island home he shared with his wife, Laurie Anderson, following complications from a liver transplant, his agent said.
John Cale, who co-founded the Velvet Underground but had a sometimes fractious relationship with his former bandmate, said the world has lost a fine songwriter and poet.
An admitted hard drinker and drug user for many years, Reed underwent a liver transplant earlier this year after he had cancelled five California concert dates scheduled in April, Reuters reports.
"I am a triumph of modern medicine," Reed posted on his website on 1 June this year, without directly acknowledging the surgery.
Reed was viewed by many as the godfather of punk music and generations of rock bands like REM, Nirvana and Sonic Youth, among many others, were influenced by him.
The Velvet Underground has long been recognized as a major musical influence on punk and art rock, as reflected in a quote often attributed to musician Brian Eno that, "The first Velvet Underground album only sold 10,000 copies, but everyone who bought it formed a band."
Fusing art and music in 1960s New York through its collaboration with artist Andy Warhol, the band never achieved much commercial success, but revolutionized rock in the 1960s and 1970s.
Reed has been widely credited with expanding the lexicon of rock 'n' roll with provocative lyrics that chronicled androgyny, illicit sex, and drug abuse, notably in the song Heroin, in which he declares, "It's my wife, and it's my life."
He often tackled controversial topics, including sex and drug addiction. Speaking in London last year, he said every performance should be unique.
"Why you would sit around trying to mimic yourself is beyond me. That's anti everything I got involved with this for, which is to have fun and play and make things up. Not to sit around copying myself - I'd rather have my toes cut off and fed to a union representative."
Walk on the Wild Side became Reed's only top-20 hit single, though it contained lyrical references to transexuality, drugs and male prostitution.
Lou Reed was married three times, the latest to recording and performance artist Laurie Anderson in 2008, and in recent years took an intense interest in photography, staging exhibitions of his work.