He was born in Athens on 15 or 19/12/1919. A stage director and professor of theater, he was born to an American mother and a Greek father who was an admiral and an attaché at the Greek Embassy in Vienna. He studied at Vienna’s Conservatory and University and earned a doctorate in economic history from the University of Leipzig. In 1941 he started to work as a stage director with the newly established Greek National Opera, beginning with the opera The Abduction from the Seraglio [Die Entführung aus dem Serail]. In 1942 he directed young Maria Callas in her first interpretation of Tosca. In the end of 1943, he joined the guerrilla forces and collaborated with the intelligence of the Allies. In 1945 he returned to Vienna. He studied under the distinguished Austrian director Herbert Graf, a supporter of realistic directing who recommended Yannopoulos to the Metropolitan Opera of New York, where the latter was hired as a Principal Director in 1946. During his 31 years at the Met, he directed 24 operas and was credited for bringing in several prominent visiting artists such as Callas, Tebaldi and Schwarzkopf. He worked for big opera houses in America and Europe and headed major music institutions in the United States and Canada. During the years 1941-1943 and 1971-1991 he directed a particularly broad range of operas of the basic and contemporary repertory at the Greek National Opera (Olympia Theatre and Odeon of Herodes Atticus: Carmen, Die Fledermaus, Cavalleria rusticana, Aida, Fidelio, Medea [Medée],Orpheus and Eurydice (Orfeo ed Euridice), Constantine Palaelogos by Kalomiris, Boris Godunov, Stravinsky’s The Rake’s Progress, Händel’s Giulio Cesare, Ariadne on Naxos, etc. In 1955, upon his invitation by Minister Georgios Rallis of the Papagos government, he founded and staged the Athens Festival for the first time. In 1958, he served as artistic director of the GNO for a brief period of two months. // Last update of the biography: December 2015 - The list of productions below is continually updated.