The House of Grimaldi is associated with the history of the Republic of Genoa, Italy, and of the Principality of Monaco. The Grimaldi dynasty is a princely house originating in Italy, founded by the Genoese leader of the Guelphs, Francesco Grimaldi, who in 1297 took the lordship of Monaco along with his soldiers dressed as Franciscans. In that principality his successors have reigned to the present day. During much of the Ancien Regime the family spent much of its time in the French court, where from 1642 they used their French title of Duke of Valentinois. The current head of the family is Albert II of Monaco, Sovereign Prince of Monaco, son and successor of Prince Rainier III and the princess consort Grace of Monaco, formerly Grace Kelly.
https://en.wikipedia.org/wiki/House_of_Grimaldi