Doug Parkinson, billed as "Australia's greatest soul voice", has died at his Sydney home aged 74.
Publicist Lionel Midford announced the singer's death in a statement on Monday evening.
"Just received the saddest news that Doug Parkinson, the legendary Australian recording artist with a powerful and soulful voice. He passed away suddenly at home," Mr Midford said.
"Doug Parkinson was widely considered one of the most unusual and influential singer/songwriters in the history of contemporary music."
Parkinson led the band Strings and Things from 1965, The Questions from 1966, Doug Parkinson in Focus from 1968, Fanny Adams from 1971 and The Life Organisation from 1973.
He had a major hit with his version of The Beatles classic Dear Prudence in 1969 followed up by his own hit Without You.
Parkinson took major stage roles in The Who's rock opera Tommy, The Wizard of Oz and Jesus Christ Superstar, recorded albums including No Regrets and Heartbeat to Heartbeat along with ads, radio station promos and rugby league team songs.
He appeared alongside many international stars including The Who, The Small Faces, The Temptations, The Pointer Sisters, Bob Marley and The Wailers and Randy Crawford.
In 2019 he toured NSW with a tribute to English rock legend Joe Cocker in which he was billed as "Australia's greatest soul voice".
He is survived by his wife Suzie and sons John and Daniel.