Wilhelm (Given names: Georg Wilhelm August Heinrich Belgicus; 14 June 1792, Kirchheimbolanden – 20/30 August 1839, Bad Kissingen) was joint sovereign Duke of Nassau, along with his father's cousin Frederick Augustus, reigning from 1816 until 1839. He was also sovereign Prince of Nassau-Weilburg from 1816 until its incorporation into the duchy of Nassau.
Frederick Augustus died on 24 March 1816 and Wilhelm inherited the Usingen territories and became sole sovereign of the Duchy of Nassau.
On 9 January 1816, he succeeded his father, Duke Frederick William, as the Prince of Nassau-Weilburg and joint Duke of Nassau with his cousin, Frederick Augustus, of the Nassau-Usingen branch of his family. When his cousin and co-Duke died on 24 March 1816, Wilhelm inherited the Usingen territories and became sole ruler of the Duchy of Nassau. He kept the title of Duke of Nassau for the rest of his reign.
Prince Wilhelm Karl Heinrich Friedrich of Nassau-Weilburg (Biebrich, 8 September 1819 – Biebrich, 22 April 1823).
Prince Moritz Wilhelm August Karl Heinrich of Nassau-Weilburg (Biebrich, 21 November 1820 – Vienna, 23 March 1850), unmarried and without legitimate issue.
Princess Marie Wilhelmine Luise Friederike Henriette of Nassau-Weilburg (Biebrich, 5 April 1822 – Biebrich, 3 April 1824).
Prince Wilhelm Karl August Friedrich of Nassau-Weilburg (Biebrich, 12 August 1823 – Biebrich, 28 December 1828).