He wasn't a household name, but Ian McDonald was a big part of some big hits. 

He was a founding member of the original Foreigner, and played on tunes like "Cold As Ice," "Hot Blooded" and "Feels Like The First Time." He was also part of the King Crimson classic LP "In The Court of the Crimson King." And he performed on T. Rex's "Get It On (Bang A Gong.)"

There's no word on the cause of death, but he was 75. 

Ian McDonald, Founding Member of Foreigner and King Crimson, Dies at 75