Philipp Melanchthon (1497–1560) was a theologian and one of the leaders of the German Reformation. It is unlikely Holbein ever met him; and he may have based this portrait on pictures by Cranach or Dürer (Buck, p. 71). Holbein also painted a decorative lid for this small painting. (https://commons.wikimedia.org/wiki/File:Hans_Holbein_the_Younger_-_Philipp_Melanchthon_(Lower_Saxony_State_Museum).JPG)