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:
William I of Württemberg
"Russia": Another paternal aunt of William's, Sophie, married the future Paul I of Russia and took the name Maria Feodorovna. This family tie to Russia had important political consequences for the later Kingdom of Württemberg since the reorganisation of Europe in the wake of the Congress of Vienna. William's second wife, Catherine Pavlovna, was his first cousin as the daughter of Paul and Maria Feodorovna. After Catherine died in 1819, the family relationship with Russia was renewed with the wedding of William's eldest son, Charles, to Grand Duchess Olga Nikolaevna. Olga was the granddaughter of Maria Feodorovna and the niece of William's second wife, Catherine. Her father was Nicholas I and her mother was Alexandra Feodorovna, the sister of the Prussian kings Frederick William IV and William I, later the German Emperor.