Rainier I of Monaco (1267 - 1314) was the first sovereign Grimaldi ruler of the area now known as Monaco. He also held the title of Lord of Cagnes. Cagnes being the town where in 1309 he established a stronghold, today known as the Chateau Grimaldi. The oldest of the three sons of Lanfranco Grimaldi, French Vicar of Provence, by his wife, Aurelia del Carretto (who later remarried with his late husband's nephew, François Grimaldi), Rainier joined his stepfather and a group of men to take the castle on the Rock of Monaco; the event is commemorated on the Monegasque coat of arms, where the supporters are two monks armed with swords (because Francois dressed as monk and opened the gates of Monaco's castle). Rainier held the citadel of Monaco for four years before departing on April 10, 1301. In 1304 he was appointed admiral of France after winning the Battle of Zierikzee. He married twice. Firstly, Salvatica, daughter of Giacomo del Carretto, Margrave of Final. They had four children:
- Charles I, his successor.
- Vinciguerra; who married Constancia Ruffa.
- Salvaggia; who married Gabriel Vento.
- Luca, Lord of Villefranche; married firstly Tedise, daughter of Daniel Cibo, and secondly Catarina Carracioli.
Secondly, Rainier I married Andriola Grillo. This marriage was childless.
