According to Entertainment Weekly:

Avant-garde rock legend and visual artist Don Van Vliet, who performed under the name Captain Beefheart, passed away today at age 69. A representative of New York City’s Michael Werner Gallery, which hosted several shows of his paintings, confirms the sad news to EW. Van Vliet died of complications from multiple sclerosis at a hospital in Northern California this morning..

• Captain Beefheart: http://en.wikipedia.org/wiki/Captain_Beefheart