Jacques I may refer to: Jacques I, Prince of Monaco (1689–1751), the Prince of Monaco Jacques I, Emperor of Haiti (1758–1806), the Emperor of Haiti Pretenders
Prince Jaime, Duke of Anjou and Madrid (1870–1931), the Duke of Madrid and Legitimist pretender to the defunct French throne as "Jacques I"
Self-proclaimed monarchs
Jacques Lebaudy (1868-1919), the self-proclaimed "Emperor of the Sahara"