Ian McDonald, founder of King Crimson and later of Foreigners, died at the age of 75 in New York.
This was announced by the artist's son, Max, who wrote in a note shared by the King Crimson label on social media that his father had died on February 9 of cancer.
"He was incredibly brave and never lost his kindness or his sense of humor even when things were tough," wrote the McDonald's son.
"My father was a brilliant and intuitive musician, a kind soul and a wonderful father. He will live forever through his beautiful music and the love of his fans."
Born in Osterley, England, in 1946, McDonald was a multi-instrumentalist and songwriter and played both saxophone and keyboards in King Crimson.
He also collaborated on the compositions of the band's 1969 debut album, 'In The Court of the Crimson King'.
"Ian's contribution to King Crimson has been invaluable and profound," reads a statement from Discipline Global Mobile, the band's record label.
However McDonald soon left the group due to disagreements with the co-founder of the group Robert Fripp, while collaborating on the band 'Red', 1975.
Later he founded the Anglo-American band 'Foreigner' with guitarist and songwriter Mick Jones , playing a variety of instruments and also singing.
In addition to the saxophone and keyboards, McDonald also played the flute, vibraphone and guitar.
He had recently played with the '21st Century Schizoid Band', made up of alumni of King Crimson.
In 2017 he formed another group, 'Honey West', in which he plays himself, on bass,