Albert of Prussia (17 May 1490 – 20 March 1568) was the last Grand Master of the Teutonic Knights, who after converting to Lutheranism, became the first monarch of the Duchy of Prussia, the secularized state that emerged from the former Monastic State of the Teutonic Knights. Albert was the first European ruler to establish Lutheranism, and thus Protestantism, as the official state religion of his lands. He proved instrumental in the political spread of Protestantism in its early stage, ruling the Prussian lands for nearly six decades (1510–1568).