Samogitia or Žemaitija is one of the five cultural regions of Lithuania and formerly one of the two core administrative divisions of the Grand Duchy of Lithuania alongside Lithuania proper. Žemaitija is located in northwestern Lithuania. Its largest city is Telšiai, while Šiauliai, where Aukštaitian dialect is being spoken, is sometimes also included into Samogitia. Samogitia has a long and distinct cultural history, reflected in the existence of the Samogitian language.

The Duchy of Samogitia was an administrative unit of the Grand Duchy of Lithuania from 1422. Between 1422 and 1441 it was known as the Eldership of Samogitia. Since the 1540s the Grand Duke of Lithuania also held the title of Duke of Samogitia, although the actual ruler of the province, responsible to the Grand Duke, was known as the General Elder of Samogitia who was self-elected by the Samogitian nobility.