Oszkár Kálmán was the first lead of a one act opera by which composer?
Oszkár Kálmán: Oszkár Kálmán (19 June 1887 - 17 September 1971) was a Hungarian bass, remembered as the first Bluebeard. Bluebeard's Castle: Bluebeard's Castle (Hungarian: A kékszakállú herceg vára ; literally: "The Blue-Bearded Duke's Castle") is a one-act opera by Hungarian composer Béla Bartók.
Béla Bartók