Joyce DiDonato
Joyce DiDonato ("née" Flaherty; born February 13, 1969) is an American operatic lyric-coloratura mezzo-soprano notable for her interpretations of the works of Handel, Mozart, and Rossini.
 She has performed with many of the world's leading opera companies and orchestras, and in 2012 and 2016 won the Grammy Award for Best Classical Vocal Solo.
Johanna Meier
Johanna Meier (born February 13, 1938) is an American operatic soprano.
 She has been described as "one of the foremost Wagnerian sopranos of her era".
 She had an international career, including fourteen years at the Metropolitan Opera and three summers singing the role of Isolde in Wagner's "Tristan und Isolde" for the Bayreuth Festival—the Festival's first American Isolde.
Diane Curry
Diane Curry (born February 26, 1938) is an American operatic mezzo-soprano who is particularly known for her performances of the works of Richard Strauss, Richard Wagner, and Giuseppe Verdi.
 She was notably the mezzo-soprano soloist on the 1987 recording of Verdi's "Requiem" by the Atlanta Symphony Orchestra & Chorus and conductor Robert Shaw which won the 1988 Grammy Award for Best Choral Performance.
Zheng Cao
Zheng Cao (July 9, 1966February 21, 2013) was a Chinese-born, American operatic mezzo-soprano known for her signature role of Suzuki in "Madama Butterfly".
 She performed this role with opera companies such as San Francisco Opera, Grand Théâtre de Genève, Pittsburgh Opera, Vancouver Opera, Washington National Opera, San Diego Opera, and under the baton of Seiji Ozawa with the Boston Symphony Orchestra.
 Her portrayal of the role of Cherubino in "The Marriage of Figaro" also earned her recognition at several American opera companies, including San Francisco Opera, Pittsburgh Opera, and Houston Grand Opera.
 She died from lung cancer in San Francisco, California in 2013.
Mignon Nevada
Mignon Nevada (14 August 1886 – 25 June 1971) was an English operatic soprano.
 She was born in Paris, daughter of the American operatic soprano Emma Nevada and her English husband Raymond Palmer.
 She was named after the title character of the 1866 opera "Mignon", written by her godfather, French composer Ambroise Thomas.
 Her voice was light and agile, and her mother trained her to be a coloratura soprano, although Sir Thomas Beecham thought this was a mistake, that she should have been a mezzo-soprano instead.
Lawrence Brownlee
Lawrence Brownlee (born 1972) is an American operatic tenor particularly associated with the bel canto repertoire.
 Describing his voice, Speight Jenkins, general director of the Seattle Opera, said: "There are other singers that sing this repertory very well, but I don't think anyone else has quite as beautiful a sound and as rounded a tone," and praise his "incredible top notes", adding about his high F (F) in "Credeasi, misera": "With him it's not a scream, it's a beautiful sound."
 Mezzo-soprano Joyce DiDonato adds: "He is always in service of the music.
 His natural instrument is just incredibly beautiful.
 The word 'honey' comes to mind.
 He also has technical prowess and agility."
John Brancy
John Brancy (born November 14, 1988) is an American operatic baritone performing with leading opera companies around the world.
 He is of Polish, German, English and Irish descent.
 He is married to the Canadian operatic mezzo-soprano Wallis Giunta.
Nell Rankin
Nell Rankin (January 3, 1924 – January 13, 2005) was an American operatic mezzo-soprano.
 Although a successful opera singer internationally, she spent most of her career at the Metropolitan Opera where she worked from 1951-76.
 She was particularly admired for her portrayals of Amneris in Verdi's "Aida" and the title role in Bizet's "Carmen". "
Opera News" said, "Her full, generous tone and bold phrasing, especially in the Italian repertory, were unique among American mezzos of her generation.
Beatrice Krebs
Beatrice Krebs (March 12, 1924 – February 5, 2011) was an American operatic mezzo-soprano, musical theatre actress, and voice teacher.

Question: Joyce DiDonato ("née" Flaherty; born February 13, 1969) is an American operatic lyric-coloratura mezzo-soprano
Answer: leading opera companies