Blanche Thebom, a mezzo-soprano who sang more than 350 performances with the Metropolitan Opera in New York, has died at age 94. From the 1944 to 1967, Thebom was a star of the Met, part of a wave of American opera singers to gain international fame. She was best known for her Wagner performances, including roles as Brangaene in "Tristan and Isolde" and Fricka in "Die Walkuere."