Duke Pius August in Bavaria, full German name: Pius August Herzog in Bayern (born 1 August 1786 in Landshut, Electorate of Bavaria; died 3 August 1837 in Bayreuth, Kingdom of Bavaria) was a Duke in Bavaria as a member of the Palatine Birkenfeld-Gelnhausen line of the House of Wittelsbach. Pius August was a grandfather of Empress Elisabeth of Austria through his son Duke Maximilian Joseph in Bavaria, as well as a great grandfather of Queen Elisabeth of the Belgians and an ancestor of the current generations of the Belgian and Italian Royal Families and the Grand Ducal Family of Luxembourg .

Born in Landshut, Pius August was the third child of Duke Wilhelm in Bavaria and his wife Countess Palatine Maria Anna of Zweibrücken-Birkenfeld.

Pius August married Princess Amélie Louise of Arenberg, daughter of Duke Louis Marie of Arenberg and his wife Marie Adélaïde Julie de Mailly, dame d'Ivry-sur-Seine, on 26 May 1807 in Brussels. Pius August and Amélie Louise had one son:

In 1815, Pius August became an honorary member of the Bavarian Academy of Sciences and Humanities. He loved to travel.

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