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 his solo hit I Believe in Father Christmas.
He died on Wednesday after “a long and stubborn battle with cancer”, said his manager.
The news comes nine months after Lake’s band-mate Keith Emerson died.
Keyboardist Emerson died of a self-inflicted gunshot wound, coroners in the US said.
His death comes on the 36th anniversary of Beatle legend John Lennon.