Leopold, Prince of Hohenzollern

Leopold, Prince of Hohenzollern (German: Leopold Stephan Karl Anton Gustav Eduard Tassilo Fürst von Hohenzollern) (22 September 1835 – 8 June 1905) was the head of the Swabian branch of the House of Hohenzollern, and played a fleeting role in European power politics, in connection with the Franco-Prussian War.

He was born into the dynasty's surviving Sigmaringen branch, which inherited all the dynasty's Swabian lands when the Hohenzollern-Hechingen branch became extinct.

Leopold's parents were Josephine of Baden and Karl Anton, Prince of Hohenzollern. Leopold was the older brother of King Carol I of Romania and father of the future King Ferdinand of Romania. Carol ascended the Romanian throne in 1866, and Leopold renounced his rights to the Romanian succession in favor of his sons in 1880.

After the Spanish Revolution of 1868 that overthrew Queen Isabella II, Leopold was offered the Spanish Crown by the new government. This offer was supported by the Prussian Prime Minister Otto von Bismarck, but opposed by the French Emperor Napoleon III on the grounds that the installation of a relative of the Prussian king would result in the expansion of Prussian influence and the encirclement of France. Leopold was forced to decline the offer.

Additional demands made by the French government heightened diplomatic tensions between Paris and Berlin; deliberate or accidental mistranslations of a diplomatic communique, the Ems Telegram, also known as the Ems Dispatch, led to the declaration of war by France. Prussia's speedy mobilization, with the support of the other members of the North German Confederation, resulted in French defeat, the capture of Napoleon and collapse of his government, loss of Alsace and part of Lorraine and huge compensation to Germany and the institution of the French Third Republic, and the creation of the German Empire.

In 1861 Leopold married Antonia of Portugal, daughter of Queen Maria II of Portugal and King Ferdinand II of Portugal. They had the following children:

• William (1864–1927); succeeded as Prince of Hohenzollern
• Ferdinand (1865–1927), King of Romania
• Karl Anton (1 September 1868–21 February 1919); married Princess Joséphine Caroline of Belgium

Had Leopold succeeded to the Spanish throne, he could possibly found a second Germanic dynasty in Spain since the extinction of the House of Austria less than two centuries prior.