Fiorenza Cossotto (born April 22, 1935) is an Italian mezzo-soprano. She is considered by many to be one of the greatest mezzo-sopranos of the 20th century.
Born on April 22, 1935 in Crescentino, Province of Vercelli, Italy, Cossotto attended the Turin Academy of Music and graduated top of her class. After her studies with Mercedes Llopart, she made her operatic debut as Sister Matilde in the world premiere of Poulenc's Dialogues of the Carmelites in 1957 at La Scala in Milan. Her international debut was at the 1958 Wexford Festival as Giovanna Seymour in Donizetti's Anna Bolena. Her Covent Garden debut was in 1959 as Neris in Cherubini's Médée, with Maria Callas in the title role. A 1962 performance of the lead in La favorita at La Scala led to wider fame and she made her American debut in the same role in 1964 at the Lyric Opera of Chicago and as Amneris at the Metropolitan Opera in 1968.
Altogether between the seasons of 1967–68 and 1988–89 she gave 148 performances at the Met (exclusively leading roles). She was considered an expert in portrayals of major mezzo/contralto roles in mid-19th-century Italian opera; e.g. Favorita, Amneris, Azucena, Eboli, Preziosilla, Maddalena, Ulrica and Laura. She also essayed Carmen, Mozart's Cherubino, Urbain in Meyerbeer's Les Huguenots, Bellini's Romeo and Marfa in Khovantschina.
She kept on singing, and in 2005 she celebrated her 70th birthday with a performance of Suor Angelica at the Théâtre Royal in Liège, Belgium.
She was married to the Italian bass Ivo Vinco for over 40 years (ending in divorce). Their only child was a son, Roberto.