|Intro||Count of Nassau-Siegen|
|Birth||23 February 1606 (Dillenburg)|
|Death||5 April 1674 (Bergen op Zoom)|
George Frederick Louis of Nassau-Siegen, called "Fritz", (b. 23 February 1606 in Dillenburg, d. 5 April 1674 in Bergen op Zoom) was Count of Nassau-Siegen (from 1664: Prince of Nassau-Siegen), Count of Katzenelnbogen, Vianden and Diez, Baron of Beilstein.
George Frederick was the son of John VII, Count of Nassau (1561–1623) and his second wife, Princess Margareth of Schleswig-Holstein-Sonderburg (1583–1658). His brother was John Maurice, Prince of Nassau-Siegen ("The Brasilian") (1604–1679), his sister Amalia Magdalena of Nassau-Siegen (1613–1669).
George Frederick was a soldier and became on 19 November 1627 Captain (Hauptmann) of the infantry of the Dutch Republic. On 3 January 1633 he became Rittmeister of the cavalry. On 9 January 1637 he returned as Major to the infantry where he was promoted to Oberst on 8 January 1642. From 30 October 1648 to 1658, George Frederick was Stadtholder of Rheinberg. On 25 October 1658 he became Gouverneur of Bergen op Zoom. In 1661 he became knight of the highest order of Denmark, the Order of the Elephant. From 1638 until his death after an injury on the battlefield 1674, he was ruler of Nassau-Siegen and successor of John VIII, Count of Nassau-Siegen.
On 4 June 1647 he married Mauritia Eleonora of Portugal (1609–1674) in The Hague. The marriage produced no children.
George Frederick had two illegitimate children:
- a daughter
- Margaretha Sofia (d. 1737), married Johann Fer in 1669.