The Prince-Archbishopric of Bremen — not to be confused with the modern Archdiocese of Hamburg, founded in 1994 — was an ecclesiastical principality (787–1566/1648) of the Holy Roman Empire and the Catholic Church that after its definitive secularization in 1648 became the hereditary Duchy of Bremen. The prince-archbishopric, which was under the secular rule of the archbishop, consisted of about a third of the diocesan territory. The city of Bremen was de facto and de jure not part of the prince-archbishopric. Most of the prince-archbishopric lay rather in the area to the north of the city of Bremen, between the Weser and Elbe rivers. Even more confusingly, parts of the prince-archbishopric belonged in religious respect to the neighbouring Diocese of Verden, making up 10% of its diocesan territory.

The Archdiocese of Hamburg is a Latin Church ecclesiastical territory or diocese of the Catholic Church in the north of Germany and covers the Federal States of Hamburg and Schleswig-Holstein as well as the Mecklenburgian part of the Federal State of Mecklenburg-Vorpommern. In terms of surface area it is the largest in Germany. It is characterized by its situation as a diocese in the Diaspora. Seat of the archbishop is the New St. Mary's Cathedral in Sankt Georg, Hamburg. On January 26, 2015 Stefan Heße, Generalvikar of the Archdiocese of Cologne, was appointed Archbishop of Hamburg.