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:
Maria Feodorovna (Sophie Dorothea of Württemberg)
In 1773, Sophie Dorothea was among the group of German Princesses considered as possible wives of the heir to the Russian throne, the future Tsar Paul I. However, Sophie of Württemberg was not yet fourteen years old at the time, and Wilhelmina Louisa of Hesse-Darmstadt, a princess of a more appropriate age, was chosen instead.