| Archduke Leo Karl | |
| Spouse: | Maria-Klothilde von Thuillières |
| Full Name: | Leo Karl Maria Cyril-Methodius Habsburg-Lorraine |
| House: | Habsburg-Lorraine |
| Father: | Archduke Charles Stephen of Austria |
| Mother: | Archduchess Maria Theresa of Austria-Tuscany |
| Birth Date: | 1893 7, df=yes |
| Birth Place: | Pula, Austria-Hungary |
| Death Place: | Bestwina, Poland |
| Issue: | Countess Maria Desiderata of Habsburg Countess Mechtildis of Habsburg Countess Elizabeth of Habsburg Count Leo Stefan of Habsburg Count Hugo of Habsburg |
| Burial Place: | Local cemetery in Bestwina |
Leo Karl Maria Cyril-Methodius Habsburg-Lorraine, Archduke of Austria (5 July 1893 – 28 April 1939) was an Austro-Hungarian military officer, a member of the House of Habsburg-Lorraine. He was the fifth child and the second son of Archduke Charles Stephen of Austria and Archduchess Maria Theresia, Princess of Tuscany.
Archduke Leo Karl was his father’s answer to the Eastern European question, and became the would-be Regent of the Habsburgs' zone of influence in the Balkan region.
In 1913, Leo and his younger brother, Wilhelm, enrolled at the Theresian Military Academy in Wiener-Neustadt. Upon reaching 20 years of age, which was the age of majority in the Habsburg family, he was inducted into the Order of the Golden Fleece, a chivalric order.[1] At this age, he was also inducted into the Upper House of Parliament. He served in the Austro-Hungarian Army until the dissolution of Austria-Hungary, after which he served with great distinction in the Polish Army.
In October 1922, he married Austrian noblewoman Maria-Klothilde von Thuillières Gfn von Montjoye-Vaufrey et de la Roche (1893–1978), known among family as "Maja", at St. Stephen Cathedral in Vienna. The marriage was acceptable, although morganatic. Their children were granted the title of Count of Habsburg.
He lived on a portion of the Żywiec family estate that he and his brother, Albrecht, inherited from their father. Leo raised his children as Germans. He died of tuberculosis on 28 April 1939 at his estate in Bestwina, in southern Poland. Since he did not leave a will, the property was inherited by his wife Maja.
He was buried in the local cemetery in Bestwina, a countryside plot belonging to his family.