Princess Charlotte of Monaco, Duchess of Valentinois (Charlotte Louise Juliette Grimaldi; 30 September 1898 – 15 November 1977), was the daughter of Louis II, Prince of Monaco, and the mother of Rainier III, Prince of Monaco. From 1922 until 1944, she was the Hereditary Princess of Monaco, heir presumptive to the throne.

Born Charlotte Louise Juliette Louvet in Constantine, French Algeria, she was the illegitimate daughter of Marie Juliette Louvet, a cabaret singer, and Louis Grimaldi, then Hereditary Prince of Monaco and Duke of Valentinois, son and heir of Monaco's reigning prince, Albert I. Louis had no legitimate children or siblings, so even before he succeeded his father as Prince Louis II the principality sought to forestall a succession crisis, anticipating that its neighbor, the Republic of France, might take it amiss if the throne fell someday to Louis's legal next of kin. That heir was his cousin Wilhelm, 2nd Duke of Urach (1864–1928) who, although born and raised in Monte Carlo as the son of Princess Florestine of Monaco, was a German subject, property owner and patrilineal family member, albeit morganatically, of the ruling kings of Württemberg. On 15 May 1911 a law was passed recognizing Charlotte as Louis's daughter, and declaring her to be a dynastic member of the sovereign family. Though this act was later held to be invalid under the 1882 statutes, an Ordinance of 30 October 1918 was passed to allow her to be adopted into the dynasty instead. Louis adopted Charlotte in Paris on 16 May 1919, thereby entitling her to the surname Grimaldi, while her grandfather bestowed upon her the traditional title of the princedom's heir, Duchess of Valentinois, for life. Charlotte became heir presumptive to the throne as Hereditary Princess when her grandfather died and her father inherited the princely crown in 1922.

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