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 Sophie of Saxony
Sophie married Duke Karl-Theodor in Bavaria, fifth child and third-eldest son of Duke Maximilian Joseph in Bavaria and his wife Princess Ludovika of Bavaria, on 11 February 1865 in Dresden. Sophie and Karl-Theodor had one child:Childbirth caused severe respiratory problems for Sophie, which progressively weakened her, although she managed to recover. However, a year later she contracted a severe case of influenza that she could not overcome. Sophie died shortly before her 22nd birthday on 9 March 1867 and was interred at Tegernsee Abbey.