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:
Princess Charlotte of Württemberg
Princess Charlotte of Württemberg (9 January 1807 – 2 February 1873) was later known as Grand Duchess Elena Pavlovna, the wife of Grand Duke Michael Pavlovich of Russia. He was the youngest son of Emperor Paul I of Russia and Duchess Sophie Dorothea of Württemberg.