Former Bay City Rollers frontman Les McKeown has died aged 65, his family has told the BBC.
The Scottish pop singer fronted the Edinburgh band during their most successful period in the 1970s.
They had hits with tracks like I Only Wanna Be With You, Bye Bye Baby, Shang-a-Lang and Give a Little Love.
His family announced online on Thursday that he had died suddenly at his home on Tuesday.
The Bay City Rollers became tartan-clad sensations in the UK and US in the 1970s. They were hugely successful, selling more than 120 million records.
"They were adorable. Five cute guys at once. That's the story of rock n roll," US journalist Danny Fields told the BBC.
"The invention of boy bands became an industry thanks to the Bay City Rollers."
Recalling the 1975 tour 40 years later, Les McKeown said it was "crazy".
"We would go on and the police would make us stop because they just could not control the crowd."
Vocalist McKeown joined in 1973 and left in 1978, as the band decided to go in a more new wave direction under the new name The Rollers.
But he then re-joined for a string of comeback tours and live recordings.
As the only remaining member of the band, he toured under the name Les McKeown's Bay City Rollers up until last year.
McKeown told the Edinburgh Evening News last August that during lockdown he had "never had so much time off", and was always on the road for half of the year.
He had been mid-way through a tour in Toronto with his band Les McKeown's Bay City Rollers as the coronavirus pandemic took hold, and they all had to return home quickly. The tour had been rebooked for November 2021.