Gustav Adolph, Duke of Mecklenburg [-Güstrow] was the last ruler of Mecklenburg-Güstrow from 1636 until his death and last Lutheran Administrator of the Prince-Bishopric of Ratzeburg from 1636 to 1648.

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.