Nicolas Oreste Flagello (March 15, 1928 – March 16, 1994), was an American composer and conductor of classical music. He was one of the last American composers to develop a distinctive mode of expression based wholly on the principles and techniques of European late-Romanticism.
Flagello was born in New York City, into a very musical family. His brother Ezio Flagello was a bass who sang at the Metropolitan Opera. One of his first music teachers was the composer Vittorio Giannini, and he then studied at the Manhattan School of Music. Upon graduating (M.M., 1950) he joined the faculty, where he remained for more than 25 years. In 1955, he won a Fulbright Fellowship to study at the Accademia Nazionale di Santa Cecilia in Rome where he worked under Ildebrando Pizzetti.
As a composer, Flagello held firmly to a belief in music as a personal medium for emotional and spiritual expression. This unfashionable view, together with his vehement rejection of the serialism that dominated musical composition for several decades after World War II, hindered his music from attracting significant attention during much of his lifetime. Among his most auspicious successes were the oratorio The Passion of Martin Luther King (1968), premiered in Washington, DC, in 1974, and the opera The Judgment of St. Francis (1959), presented at the Cathedral of St. Francis in Assisi in 1982. He produced a large body of work, including six operas, two symphonies, eight concertos, and numerous orchestral, choral, chamber, and vocal compositions. In the mid-1980s, his career was cut short by a degenerative disease. He died in New Rochelle, New York, on March 16, 1994. Since his death Flagello's music has generated a greater following, and many of his major works have been recorded.