Barbara of Cilli

Barbara of Cilli married Holy Roman Emperor Sigismund and became Queen of Hungary and Bohemia, then Empress. But she wasn't ceremonial. She administered feudal estates and tax collection independently, operating as an economic and political force in her own right. In 1412, 1414, 1416, and 1418, she served as regent of Hungary when Sigismund left the kingdom. She helped create the Order of the Dragon, the chivalric society that would become one of the era's most storied orders. She died on 11 July 1451, having spent nearly four decades at the center of Central European power.