Frederick William, Grand Duke of Mecklenburg, KG (17 October 1819 – 30 May 1904) was a German sovereign who ruled over the state of Mecklenburg-Strelitz from 1860 until his death.

He was born in Neustrelitz, the son of Grand Duke Georg of Mecklenburg-Strelitz and Princess Marie of Hesse-Kassel. He spent his youth in Neustrelitz and later went to study history and jurisprudence in Bonn. After finishing his studies, he went travelling to Italy and Switzerland. He became a Doctor of Civil Law of the University of Oxford.

Friedrich Wilhelm succeeded as Grand Duke on the death of his father on 6 September 1860. During his reign, Mecklenburg-Strelitz became a member first of the North German Confederation and then the German Empire. Friedrich Wilhelm was a large land owner with more than half of the entire grand duchy his personal property.

On 12 August 1862 Friedrich Wilhelm was made a Knight of the Order of the Garter by Queen Victoria of the United Kingdom.

He died at Neustrelitz on the 30 May 1904 and was succeeded by his only son, who became Adolf Friedrich V.

Friedrich Wilhelm was married on 28 June 1843 at Buckingham Palace to his first cousin, Princess Augusta of Cambridge, a member of the British Royal Family and a granddaughter of King George III. The two were also second cousins on their fathers' side. They had two sons:

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