Stratas was born Anastasia Stratakis to a struggling immigrant Cretan family in Oshawa, near Toronto, Ontario. At age 13, she performed Greek pop songs on the radio. She graduated from The Royal Conservatory of Music in Toronto. At age 20, Stratas made her professional opera debut as Mimì in La bohème at the Toronto Opera Festival. One year later in 1959, she co-won the Metropolitan Opera National Council Auditions, appearing later that year with the Metropolitan Opera as Poussette in Manon. She created the title role in Peggy Glanville-Hicks' Nausicaa at the Herod Atticus Theatre in Athens in 1961, made her Covent Garden debut as Mimì that same year and in 1962, she made her La Scala debut as Isabella in Manuel de Falla's L'Atlántida. She continued her career with the Metropolitan Opera, moved into leading roles and performed with leading opera houses around the world, including the Bolshoi, Vienna State, Berlin, Bavarian State (Munich), Paris and San Francisco Operas as well as the Salzburg Festival. Her repertoire also included Zerlina in Don Giovanni, Despina in Così fan tutte, Cherubino and Susanna in The Marriage of Figaro, Liù in Turandot, Cio-Cio-San in Madama Butterfly, Micaëla in Carmen, Marguerite in Faust, the title role in La Périchole, Gretel in Hansel and Gretel, Lisa in The Queen of Spades, The Composer in Ariadne auf Naxos, Antonia in Les contes d'Hoffmann, Mélisande in Pelléas et Mélisande, Marenka in The Bartered Bride, Desdemona in Otello, Mme Lidoine in Dialogues des Carmélites, the title roles of Salome and Lulu, Jenny Smith in Rise and Fall of the City of Mahagonny (directed by John Dexter) and Marie Antoinette in John Corigliano's The Ghosts of Versailles. She is regarded as one of the foremost singing actresses of the twentieth century.