Prince Karl Anton of Hohenzollern-Sigmaringen (German: Karl Anton Joachim Zephyrinus Friedrich Meinrad Fürst von Hohenzollern-Sigmaringen) (7 September 1811 – 2 June 1885) was head of the Princely House of Hohenzollern-Sigmaringen, Hohenzollern from 1869 and Prime Minister of Prussia. He was the son of Charles, Prince of Hohenzollern-Sigmaringen, who abdicated in favour of his son on 27 August 1848, and his first wife Marie Antoinette Murat, niece of Joachim Murat.

After only slightly over a year ruling his family's small principality, Karl Anton abdicated in December 1849 in favor of his distant cousin, the King of Prussia, and Hohenzollern-Sigmaringen, along with the neighboring principality of Hohenzollern-Hechingen, was annexed by Prussia. After his abdication, Karl Anton became a prominent figure in Prussian politics. After the fall of the reactionary Manteuffel ministry in 1858, and the accession of Prince William as regent for his incapacitated brother, King Frederick William IV, a new, moderately liberal ministry was appointed, with Karl Anton as Minister-President. The Prince continued in this role until 1862, when he resigned in the midst of a struggle with parliament over the military budget.

After this, Karl Anton largely resigned from active politics and focused on his role as head of the Catholic branch of the Hohenzollern family, accentuated by the extinction of the Hohenzollern-Hechingen line in 1869. In 1866, his second son, Karl, was offered the throne of Romania, where he would rule for nearly forty years as Carol I. A few years later, in 1870, his eldest son, Leopold, was given a similar offer of the Spanish throne. This so-called "Hohenzollern candidacy" for the Spanish throne was one of the main factors in instigating the Franco-Prussian War.

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