Mauritius Ferber (Polish: Maurycy Ferber; 1471 – 1 July 1537) was a member of the patrician Ferber family. As Roman Catholic Prince-Bishop of Warmia (Ermland), he prevented most towns in his diocese from converting to Protestantism while the surrounding hitherto Catholic State of the Teutonic Order was transformed into the Duchy of Prussia and became the first state to adopt Lutheranism.