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:
Sophia Dorothea of Celle
On 22 November 1682, in Celle, Sophia Dorothea married her cousin, George Louis. In 1705 he would inherit the Principality of Lüneburg after the death of his father-in-law and uncle, George William, Duke of Brunswick-Lüneburg, and in 1714 the Kingdom of Great Britain and the Kingdom of Ireland and became King George I of Great Britain through his mother, Duchess Sophia, a granddaughter of James VI and I.