Mecklenburg (German pronunciation: [ˈmeːklənbʊʁk]; Low German: Mękel(n)borg [ˈmɛːkəl(n)bɔrx]) is a historical region in northern Germany comprising the western and larger part of the federal-state Mecklenburg-Western Pomerania. The largest cities of the region are Rostock, Schwerin, Neubrandenburg, Wismar and Güstrow.

The name Mecklenburg derives from a castle named Mikilenburg (Old Saxon for "big castle", hence its translation into New Latin and Greek as Megalopolis), located between the cities of Schwerin and Wismar. In Slavic languages it was known as Veligrad, which also means "big castle". It was the ancestral seat of the House of Mecklenburg; for a time the area was divided into Mecklenburg-Schwerin and Mecklenburg-Strelitz among the same dynasty.

Linguistically Mecklenburgers retain and use many features of Low German vocabulary or phonology.

The adjective for the region is Mecklenburgian or Mecklenburgish (German: mecklenburgisch); inhabitants are called Mecklenburgians or Mecklenburgers (German: Mecklenburger).