| Xavier Marie Joseph | |
| Birth Date: | 8 September 1753 |
| Birth Place: | Palace of Versailles, Versailles, France |
| Death Date: | (5 months & 14 days) |
| Death Place: | Palace of Versailles, Versailles, France |
| Burial Place: | Saint Denis Basilica |
| Father: | Louis, Dauphin of France |
| Mother: | Princess Maria Josepha of Saxony |
| House: | Bourbon |
Xavier Marie Joseph, Duke of Aquitaine (8 September 1753 - 22 February 1754) was a French prince of the House of Bourbon. He was the third surviving child and second eldest son of Louis, Dauphin of France and Maria Josepha of Saxony, and was thus the second oldest brother to the future kings Louis XVI, Louis XVIII and Charles X. He was given the courtesy title of Duke of Aquitaine upon birth and during the five months he lived he was second in line to the throne of France after his elder brother Louis Joseph, Duke of Burgundy. Xavier was baptized on 21 February 1754 in the parish of Notre-Dame of Versailles with his godfather Louis Charles de La Mothe-Houdancourt and his godmother Marie Louise Geneviève de Rohan. He died of whooping cough on 22 February 1754[1] and was buried in the Saint Denis Basilica. While Xavier's heart was buried in the abbey Val-de-Grâce.
The inscriptions on the urn containing Xavier's heart were found in 1845 in a shop and purchased by Viscount Becdelièvre, who gave them to the Crozatier museum in Puy-en-Velay:
This is the heart of Xavier Marie Joseph Duke of Aquitaine very tall very strong and very beautiful second son of Prince Louis, Dauphin of France and Dauphine Maria Josepha of Saxony died at the Chateau de Versailles on 22 February 1754 at 5 Months and 14 Days.[2]
Since he and his brother predeceased their father and grandfather, the throne of France ultimately passed to their younger brother Louis Auguste who later became Louis XVI.