His best known work is probably his portrait of Diana , Princess of Wales , completed in 1996 .
John Nelson Shanks ( December 23 , 1937 -- August 28 , 2015 ) was an American artist and painter .
John Nelson Shanks ' best known work is probably his portrait of Diana , Princess of Wales , completed in 1996 .
John Nelson Shanks ( December 23 , 1937 -- August 28 , 2015 ) was an American artist and painter .