(b Milan, c.1467; d Milan, 15 June 1516). Italian painter, the pupil and assistant of Leonardo and the most talented of his followers in Milan. He painted religious subjects and portraits (an example of each is in the National Gallery, London). His style is more prosaic than his master's, but his best work is of high quality: the beautiful female portrait known as La Belle Ferronnière (Louvre, Paris) is attributed to Boltraffio by some authorities and to Leonardo by others.