Jérôme Bonaparte, French husband of Catharina of Württemberg (d. 1860)
Jérôme-Napoléon Bonaparte (born Girolamo Buonaparte; 15 November 1784 – 24 June 1860) was the youngest brother of Napoleon I and reigned as Jerome Napoleon I (formally Hieronymus Napoleon in German), King of Westphalia, between 1807 and 1813. Historian Owen Connelly points to his financial, military, and administrative successes and concludes he was a loyal, useful, and soldierly asset to Napoleon. Others, including historian Helen Jean Burn, have demonstrated his military failures, including a dismal career in the French navy that nearly escalated into war with Britain over an incident in the West Indies and his selfish concerns that led to the deaths of tens of thousands during the Russian invasion when he failed to provide military support as Napoleon had counted upon for his campaign; further, his addiction to spending led to both personal and national financial disasters, with his large personal debts repeatedly paid by family members including Napoleon, his mother, and both of his first two fathers-in-law, and the treasury of Westphalia emptied. In general, most historians agree that he was the most selfish, self-absorbed, unsuccessful, and feckless of Napoleon's brothers.

From 1816 onward, he bore the title of Prince of Montfort. After 1848, when his nephew, Louis Napoleon, became President of the French Second Republic, he served in several official roles, including Marshal of France from 1850 onward, and President of the Senate in 1852. He was the only one of Napoleon's siblings who lived long enough to see the Bonaparte restoration.