In my own preferred genre, Cabaret, while there are stars, legends, and heavenly creatures aplenty, there really is only one contender for top spot, a singer equally revered by crooners like Sinatra and art-song singers like Joan Morris and Dawn Upshaw (and pretty much everybody in between).
She, of course, was (is, and evermore shall be) Miss Mabel Mercer, the Empress of all Saloon Singers.
Regal in her stage presence - usually seated, always elegantly gowned, often draped in a shawl put to good use as her only prop - Mercer ruled the rarefied world of club singing with poise, grace, and a voice that was, by the end, a whisper of a soprano combined with the diction of an angel.
With all due respect to mine and everybody's favorites (since I know that TJB is bound to bring up the also fabulous Miss Maye), when it comes to how sing the Great American Song: Mabel Mercer was more than Merely Marvelous. She is The Voice.
And - as is true of all Great Stars - my goodness, couldn't she just rock a turban?