The Prussian Lithuanians, or Lietuvininkai, are Lithuanians, originally Lithuanian language speakers, who formerly inhabited a territory in northeastern East Prussia called Prussian Lithuania, or Lithuania Minor, instead of the Grand Duchy of Lithuania and, later, the Republic of Lithuania. Prussian Lithuanians contributed greatly to the development of written Lithuanian, which for a long time was considerably more widespread and in more literary use in Lithuania Minor than in Lithuania proper.

Lithuania Minor, or Prussian Lithuania, is a historical ethnographic region of Prussia, where Prussian Lithuanians lived, now located in Lithuania and the Kaliningrad Oblast of Russia. Lithuania Minor encompassed the northeastern part of the region and got its name from the territory's substantial Lithuanian-speaking population. Prior to the invasion of the Teutonic Knights in the 13th century, the main part of the territory later known as Lithuania Minor was inhabited by the tribes of Skalvians and Nadruvians. The land depopulated during the incessant war between Lithuania and the Teutonic Order. The war ended with the Treaty of Melno and the land was repopulated by Lithuanian newcomers, returning refugees, and the remaining indigenous Baltic peoples; the term Lithuania Minor appeared for the first time between 1517 and 1526.