William I of Württemberg
On 24 January 1816, in Saint Petersburg, he married his first cousin, Grand Duchess Catherine Pavlovna of Russia (1788–1819), daughter of Emperor Paul I of Russia (1754–1801) and Princess Sophie Dorothea of Württemberg (1759–1828). The couple had two children:
Sophie, Duchess of Hohenberg
Sophie, Duchess of Hohenberg (; ; 1 March 1868 – 28 June 1914), was the wife of Archduke Franz Ferdinand of Austria, the heir to the Austro-Hungarian throne. Their assassination in Sarajevo sparked a series of events that eventually led to World War I.