Duke of Leuchtenberg was a title created twice by the monarchs of Bavaria for their relatives. The first creation was awarded by Maximilian I, Elector of Bavaria to his son Maximilian Philipp Hieronymus, upon whose death without children the lands passed back to his nephew Elector Maximilian II. It was re-created by Maximilian I Joseph, King of Bavaria on 14 November 1817 and awarded to his son-in-law, Eugène de Beauharnais, styled Royal Highness by personal grant, and with the style Serene Highness for his agnatic descendants. Eugène was the adopted stepson of the deposed Emperor Napoleon I of France, and had previously held the title of French prince with the style Imperial Highness. He also had been the emperor's heir in Frankfurt and briefly in Italy. King Maximilian Joseph compensated his son-in-law after he lost his other titles and named him heir to the kingdom after the male-line descendants of the royal house and next in precedence after the Royal Family.

Maximilian I Joseph was Duke of Zweibrücken from 1795 to 1799, prince-elector of Bavaria from 1799 to 1806, then King of Bavaria from 1806 to 1825. He was a member of the House of Palatinate-Birkenfeld-Zweibrücken, a branch of the House of Wittelsbach.