Greg Lake, who fronted both King Crimson and Emerson, Lake and Palmer, has died aged 69.
One of the founding fathers of progressive rock, the British musician is known for songs including In The Court Of The Crimson King and I Believe in Father Christmas.
He died on Tuesday after “a long and stubborn battle with cancer”, said his manager.
He also recorded as a solo artist, most notably scoring a major hit single in 1975 with I Believe in Father Christmas.
The news comes nine months after Lake’s band-mate Keith Emerson also died.
Keyboardist Emerson died of a self-inflicted gunshot wound, coroners in the US said.