This is a fictitious image of William the Conqueror, probably based on a woodcut in a Booke Containing the True Portraiture of the countenances and attire of the Kings of England, collected and published by the antiquarian Rev. Thomas Tynne in 1597.
It was once part of a set of paintings of Kings, Queens and “worthies”, made to hang in a long gallery or staircase. These were fashionable throughout the Tudor period.