Mecklenburg-Güstrow was a state of the Holy Roman Empire in Northern Germany, that existed on three occasions ruled by the House of Mecklenburg at Güstrow.

The House of Mecklenburg, also known as Nikloting, is a North German dynasty of Polabian origin that ruled until 1918 in the Mecklenburg region, being among the longest-ruling families of Europe. Queen Juliana of the Netherlands (1909–2004), former Queen of the Netherlands (1948–1980), was an agnatic member of this house.