Sigurd Snake-in-the-Eye — From an engraving published 1670 with the title 'Veræ effigies regum omnium qvi a primo Dan usqe Christianum IV modo regnantem imperii Danici gloria eminuerunt' - here the part depicting the Danish (semi-legendary) king Sigurd Snake-in-the-Eye (9th century).
Photo Credit: By Erico Olai Tormio (publisher) - Public Domain, https://commons.wikimedia.org/w/index.php?curid=85640713