(b Florence, c.1496; d Naples, ?c.1536).
Italian painter, active mainly in Rome, where he and Giulio Romano were Raphael's main assistants (he was nicknamed Il Fattore, which might be translated as ‘right-hand man’). Various parts of works by the master have been attributed to him (Vasari says he was employed on the tapestry cartoons for the Sistine Chapel), but he is a shadowy figure. After Raphael's death he collaborated with Giulio. A rare signed work by Penni is the Portrait of a Young Man (NG, Dublin).