| Archduchess Maria Luisa of Austria | |
| Full Name: | Italian: Maria Luisa Annunziata Anna Giovanna Giuseppa Antonietta Filomena Apollonia Tommasa |
| Princess of Isenburg and Büdingen | |
| Spouse: | Karl II, Prince of Isenburg-Birstein |
| Issue: | Prince Leopold Wolfgang Princess Antonia Princess Maria Prince Franz Joseph Prince Victor Salvator Prince Alfonso Princess Elizabeth Princess Adelaide |
| House: | House of Habsburg-Lorraine House of Isenburg-Büdingen |
| Father: | Leopold II, Grand Duke of Tuscany |
| Mother: | Princess Maria Antonia of Bourbon-Two Sicilies |
| Birth Date: | 31 October 1845 |
| Birth Place: | Florence, Grand Duchy of Tuscany |
Archduchess Maria Luisa of Austria, Princess of Tuscany (full name: Maria Luisa Annunziata Anna Giovanna Giuseppa Antonietta Filomena Apollonia Tommasa) (31 October 1845 – 27 August 1917) was a Princess of Tuscany, and later Princess of Isenburg and Büdingen.
Maria Luisa was born in Florence, the eighth child and fifth daughter of Leopold II, Grand Duke of Tuscany and his second wife, Princess Maria Antonia of the Two Sicilies. Her paternal grandparents were Ferdinand III, Grand Duke of Tuscany and Luisa of Naples and Sicily. Her maternal grandparents were King Francis I of the Two Sicilies and María Isabella of Spain, Infanta of Spain. She was baptized in Florence's Battistero di San Giovanni as Maria Luisa Annunziata Anna Giovanna Giuseppa Antonietta Filomena Apollonia Tommasa, in honor of her father's sister, Princess Maria Luisa (1798-1857), affectionately called "the little hunchback" by the people of Florence.
Maria Luisa was born in a time of peace and prosperity for the Grand Duchy of Tuscany, and she was raised in an loving family environment. However, she was first confronted with the dangers of her position at a young age, due to the Revolutions of 1848. In February 1849, the Grand Ducal family decided to go to Gaeta as a security measure. The Grand Duchess Maria Antonia traveled separately with her two younger children, Maria Luisa and Ludwig. The family remained in Gaeta for several months and was unable to return to Florence until 28 July 1849.
Later, Maria Luisa and her family were forced to flee Florence on 27 April 1859, with the outbreak of a revolution inspired by the war by France and Sardinia-Piedmont against Austria as part of the unification of Italy. The family took refuge in Austria. At the end of the war, her father Leopold II abdicated on 21 July and his son Ferdinand succeeded him as Grand Duke.
On 31 May 1865, at the age of twenty, Maria Luisa married Karl II, Prince of Isenburg-Birstein (1838–1899) in Brandeis, Bohemia. Her husband was a grandson of Karl, last sovereign Prince of Isenburg. The couple had nine children. Karl died at the age of sixty, and Maria Luisa died during World War I, in 1917. They are the ancestors of Sophie, Princess of Prussia, wife of Georg Friedrich, Prince of Prussia, the head of the House of Hohenzollern.
Maria Luisa and Karl had nine children: