The Duchy of Pomerania (12th century – 1637) is a duchy in Pomerania on the southern coast of the Baltic Sea, ruled by dukes of the House of Pomerania (Griffins).The duchy originates from the realm of Wartislaw I, a Slavic Pomeranian duke, and is extended by the Lands of Schlawe and Stolp in 1317, the Principality of Rügen in 1325, and the Lauenburg and Bütow Land in 1455.

During the High Middle Ages, it also comprises the northern Neumark and Uckermark areas as well as Circipania and Mecklenburg-Strelitz.The Dukes of Pomerania are vassals of Poland from 1122 to 1138, of the Duchy of Saxony from 1164 to 1181, of Denmark from 1185 to 1227, and of the Holy Roman Empire from 1181 to 1185 and from 1227 to 1806, including periods of vassalage to the Margraves of Brandenburg.

Most of the time, the duchy is ruled by several Griffin dukes in common, resulting in various internal partitions.

After the last Griffin duke dies during the Thirty Years' War in 1637, the duchy is partitioned between Brandenburg-Prussia and Sweden.

The Kings of Sweden and the Margraves of Brandenburg, later Kings of Prussia, become members as Dukes of Pomerania in the List of Reichstag participants.The name Pomerania comes from Slavic po more, which means Land by the Sea.