Les Mitchell about Opera Singers

Maria Callas DEFINITELY! She was THE opera diva of the Twentieth Century.
However, a lot of these singers appeared in films, most notably Melchior (quite a number of them for MGM) Lawrence Tibbett, Lily Pons, and Ezio Pinza. Dorothy Kirsten appeared in "The Great Caruso, Helen Traubel did an MGM musical and and another film with Jerry Lewis, Enrico Caruso and Geraldine Farrar appeared in silent films. Kirsten Flagstad was the most spectacular Dramatic Wagnerian soprano, possibly of all time, and was well known in Hollywood (as well as having appeared in "Big Broadcast of 1938). Placido Domingo was THE tenor from 1970-2000 (much greater as an artist than Pavarotti) and is now the CEO of the Los Angeles Opera. Ernestine Schumann Heink sang on the radio often and is considered the last true contralto.
I would think that Joan Sutherland and Marilyn Horne should have been included. Renata Tebaldi never appeared in a film, but was greatly loved and revered at the Met and in Europe.