https://en.m.wikipedia.org/wiki/Liechtenstein
Liechtenstein
33 years, 6 days
https://en.m.wikipedia.org/wiki/Alois,_Hereditary_Prince_of_Liechtenstein
Hans-Adam II
The Hereditary Prince Alois (currently Prince Regent)
In 1956, he entered the Schottengymnasium in Vienna. In 1960, he transferred to the Lyceum Alpinium Zuoz in Switzerland, earning a Swiss Matura and a German Abitur in 1965. He then worked as a bank trainee in London before enrolling at the University of St. Gallen to study business administration, graduating with a licentiate in 1969. He is fluent in English and French in addition to his native German.
https://en.m.wikipedia.org/wiki/Hans-Adam_II,_Prince_of_Liechtenstein
Countess Marie Kinsky of Wchinitz and Tettau
https://en.m.wikipedia.org/wiki/Countess_Marie_Kinsky_of_Wchinitz_and_Tettau