Gustav Adolph, Duke of Mecklenburg [-Güstrow] (26 February 1633 – 6 October 1695) 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.

[1] Gustav Adolph was born at the ducal residence in Güstrow, the son of Duke John Albert II and his third wife Eleonore Marie (1600–1657), daughter of Prince Christian I of Anhalt-Bernburg.

Their marriage produced eleven children: The death of the only surviving son, the Hereditary Prince Charles, in 1688 at the age of 23, caused a succession crisis in Mecklenburg-Güstrow.

Gustav Adolph's daughter Marie married her cousin Adolphus Frederick II of Mecklenburg, who after the death of his father-in-law claimed the Güstrow heritage, but could not prevail against the ruling duke of Mecklenburg-Schwerin.

A younger daughter, Louise in 1695 married the Danish crown prince Frederick IV and in 1699 became queen consort of Denmark.