This is Count Floris, King Williams son, and [he] was the fifteenth Count of Holland - Floris V as imagined in the 17th century
Count Floris V of Holland and Zeeland (24 June 1254 – 27 June 1296), “der Keerlen God” (God of the Peasants), is one of the most important figures of the first, native dynasty of Holland (833–1299). His life was documented in detail in the Rijmkroniek by Melis Stoke, his chronicler. He is credited with a mostly peaceful reign, modernizing administration, policies beneficial to trade, generally acting in the interests of his peasants at the expense of nobility, and reclaiming land from the sea. His dramatic murder engineered by King Edward I of England and Guy de Dampierre, count of Flanders, made him a hero in Holland.