Mauritius Ferber (Polish: Maurycy Ferber) (1471 – 1 July 1537) in Lidzbark (Heilsberg) was a member of the patrician Ferber family of Danzig (Gdańsk) in Poland. As Roman Catholic Prince-Bishop of Warmia (Ermeland), 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.
The Ferber family had immigrated in 1415 from Kalkar to Danzig. During four centuries, several members of the family served as mayor of Danzig, of which four served simultaneously. Johann Ferber was (nicknamed iron) mayor from 1479 until his death in 1501, his son Eberhard Ferber (1463–1529) served from 1510 until 1526, and Eberhard's son Konstantin Ferber (1520–1588) from 1555 until his death in 1588, with others of the name Constantin Ferber holding the office later on.
Mauritius Ferber had stayed in England in 1497 before returning to his home town, where he in 1498 claimed to be engaged to Anna Pilemann, a wealthy heiress, by presenting parts of her clothes as proof. This led to a feud involving several families and to a lawsuit at the papal court. Mauritius successfully presented his case as plaintiff in Rome, but by that time the bride was married to someone else. In 1507, a compromise among the families was negotiated by Eberhard, while Mauritius spent time in Italy serving a cardinal and the pope before becoming a priest, as did Tiedemann Giese, another wealthy merchant from Danzig, and a relative of the Ferber family who would become Mauritius' coadjutor in 1523. He acquired several sinecures, became canon in Warmia, Lübeck, Reval and Dorpat, of St. Peter in Danzig in 1512 and of Danzig's (St. Mary's Church) in 1514. Back in Siena, on 3 September 1515 he was promoted to doctor of both laws.