"Leonard Warren was the great Verdi baritone of our times ... Lord Byron said of the fabled Shakespearean actor Edmund Kean that seeing him was one of the great consolations, and that was Leonard Warren’ Tony Randall, from the foreword to the biography by Mary Jane Phillips-Matz.

What ever subjective effect the voice of Leonard Warren had or has on the listener, whether live or on record, there can be no doubt that in his era, like Lawrence Tibbett his immediate predecessor, Warren occupied a special place in the pantheon of American opera singers. In spite of serious competition from other great baritone voices active then, such as Francesco Valentino, Richard Bonelli, Robert Weede, Igor Gorin, Robert Merrill and Donald Dixon, Warren was to the opera going public at the Metropolitan Opera, New York ‘the King’.