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:
Prince Paul of Württemberg
Prince Paul of Württemberg (Paul Heinrich Karl Friedrich August; 19 January 1785 – 16 April 1852) was the fourth child and second son of King Frederick I and his wife, Duchess Augusta of Brunswick-Wolfenbüttel.