Albert of Prussia (1490-1568) was a significant figure in the history of the Teutonic Knights and the Duchy of Prussia. He was the last Grand Master of the Teutonic Order and played a crucial role in the transition of the order from a religious military organization to a secular duchy. In 1525, he secularized the order's territories and became the first Duke of Prussia. As a ruler, Albert promoted the Protestant Reformation in his duchy, aligning himself with Martin Luther's teachings. His reign marked the beginning of the Duchy of Prussia as a significant political entity in Northern Europe, influencing the region's religious and cultural landscape.