Ferdinand III, Grand Duke of Tuscany, or, more fully, His Imperial and Royal Highness Ferdinando III Giuseppe Giovanni Baptista Grand Duke of Tuscany, Archduke of Austria, Prince of Hungary and Bohemia, (May 6, 1769 – June 18, 1824; born and died in Florence, Italy), was the son of Emperor Leopold II (1747 - 1792) and his wife Maria Luisa of Spain (1745 - 1792).

He was married on August 15, 1790, at Naples, Italy, to Luisa Maria Amelia Teresa of the Two Sicilies (July 27, 1773 - September 19, 1802), daughter of Fernando I of the Two Sicilies (1751 - 1825) and his wife Marie Caroline of Austria (1752 - 1814).

Their children were:

1. Carolina Ferdinanda Theresia (1793 - 1802)
2. Franz Leopold (1794 - 1800)
3. Leopold II (1797 - 1870)
4. Marie Louise Josephe Christine Rose (1799 - 1857)
5. Maria Teresa (1801 - 1855)
6. [?] (1802)

His was married again on May 6, 1821 at Florence, Italy to Maria of Saxony (or, more fully, Her Highness Maria Ferdinande Amalia Xaveria Theresia Josepha Anna Nepomucena Aloysia Johanna Vincentia Ignatia Dominica Franziska de Paula Franziska de Chantal, Duchess of Saxony) (April 27, 1796 - January 3, 1865), daughter of Maximilian of Saxony (1759 - 1838) and his wife Caroline of Bourbon-Parma (1770 - 1804). There were no children born of this second marriage.

Ferdinand succeeded his father as Grand Duke of Tuscany in 1790, and ruled in Tuscany until 1801, when he was forced by Bonaparte to give up Tuscany to the Bourbons of Parma, who turned it into the Kingdom of Etruria. Ferdinand was compensated by being given the secularized lands of the Archbishop of Salzburg and several other ecclesiastical princes in Germany, and was made a Prince-elector of the Holy Roman Emperor. By the Treaty of Pressburg of 1805, Ferdinand was made to give up Salzburg, which was annexed by his brother, the Emperor of Austria, and instead became Duke of Würzburg, a new state created for him from the old Bishopric of Würzburg. He remained in this role until Napoleon's fall in 1814, when he returned to Tuscany, which he ruled until his death.

|- style="text-align: center;" | width="30%" |Preceded by:
Hieronymus von Colloredo, Archbishop of Salzburg | width="40%" style="text-align: center;" |Prince-Elector and Duke of Salzburg
1803–1806 | width="30%" |Succeeded by:
annexed to Austria

|- style="text-align: center;" | width="30%" |Preceded by:
part of Bavaria | width="40%" style="text-align: center;" |Duke of Würzburg
1806–1814 | width="30%" |Succeeded by:
part of Bavaria

|- style="text-align: center;" | width="30%" |Preceded by:
annexed to France | width="40%" style="text-align: center;" |Grand Duke of Tuscany
1814–1824 | width="30%" |Succeeded by:
Leopold II