Pomesanians were a Prussian clan. They lived in Pomesania, a historical region in modern northern Poland, located between the Nogat and Vistula Rivers to the west and the Elbląg River to the east. It is located around the modern towns of Elbląg and Malbork. As the westernmost clan, the Pomesanians were the first of the Prussians to be conquered by the Teutonic Knights, a German military crusading order brought to the Chełmno Land to convert the pagans to Christianity. Due to Germanization and assimilation, Pomesanians became extinct some time in the 17th century.

Old Prussians, Baltic Prussians or simply Prussians were a Baltic people that inhabited the region of Prussia, on the southeastern shore of the Baltic Sea between the Vistula Lagoon to the west and the Curonian Lagoon to the east. As Balts, they spoke an Indo-European language of the Baltic branch now known as Old Prussian and worshipped pre-Christian deities. Their ethnonym was later adopted by predominantly Low German-speaking inhabitants of the region.