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:
Dorothea Sophia, Abbess of Quedlinburg
She was the fourth child and second daughter of Friedrich Wilhelm I, Duke of Saxe-Weimar, and his first wife, Sophie of Württemberg.