Grimaldi , one of the four great patrician families of Genoa. They derive their descent from Grimoald, mayor of the palace under the Frankish king Childebert II., and first made their appearance in northern Italy in the 10th century. In 980 they gained posses-sion of the lordship of Monaco, of which they remained the hereditary princes for upward of seven centuries. They belonged to the Guelph faction, and cooperated with the Fies-chi in those incessant struggles with the Ghi-bellines, headed by the Doria and Spinola families, which kept Genoa in a turmoil; and notwithstanding the law of 1339 excluding the nobles, both Guelph and Ghibelline, from holding supreme authority in the state, they continued to exert the greatest influence in the government of their country. The Gri-maldis possessed large estates in France and Italy. Branches of this family still exist in Nice and southern France. Ranieri II. was the first Genoese who led the fleet of the republic beyond the strait of Gibraltar. As an ally of Philip the Fair of France, he defeated in 1304 the Flemish fleet under Guy of Flanders, whom he took prisoner.

Carlo II., sur-named the Great, commanded the Genoese crossbowmen in the battle of Crecy. His troops, rendered helpless by the damage which a heavy shower had caused to their bowstrings, were attacked not only by the English, but also by the French, who were enraged at the falling back of their allies, and a dreadful carnage ensued, in which their commander was killed (1346). Antonio, an admiral, in 1332 avenged the aggressions of the Catalonians and Aragonese by ravaging their coasts. The supremacy which the Genoese thus gained was maintained till 1353, when the combined Catalonian and Venetian fleets, under command of Nicolo Pisani, inflicted a disastrous defeat upon Grimaldi off the coast of Sardinia, by which the naval strength of Genoa was for a time prostrated. Giovanni, in the service of the Milanese, gained a decided victory over the Venetian fleet under Trevesani on the Po, in 1431, taking numbers of galleys and immense spoils. Domenico distinguished himself as a zealous churchman, and also as a naval commander at the battle of Lepanto (1571). He was advanced to the dignity of cardinal, and extirpated heretical doctrines from his diocese. Geronimo, who died in 1685 at the age of 89, was also an ecclesiastic, and as bishop of Aix effected some very wholesome reforms in his diocese.

He annually distributed 100,000 livres in alms. He was sent as nuncio to Germany by Urban VIII., who made him a cardinal.