Although overshadowed by his dramatic death onstage during a performance, the career and accomplishments of American baritone, Leonard Warren (1911-1960) were significant. A leading performer with the Metropolitan Opera for over twenty years, Warren excelled in the Verdi repertory. As a member of the first generation of American-born opera singers to develop a truly international reputation, his success also helped to solidify their position within that prestigious company.

Born Leonard Warenoff, the son of Russian immigrants, in the Bronx, he enjoyed a typical middle-class Jewish upbringing of the time and later shortened his surname to Warren when he became a professional singer. Encouraged by an aunt, Leonard received his first formal voice lessons as a teenager at the Greenwich House Music School. Although his talent was apparent, his family remained unconvinced of the feasibility of a career in music. Following his graduation from Evander Childs High School, Warren briefly worked at his father's firm in the wholesale fur trade and took evening business classes at Columbia University.

After a few more years of haphazard musical study and odd jobs, however, Warren decided to pursue his goal of becoming a professional singer more seriously. Early opportunities included appearances on the WOR radio station in New York City and a 1934 summer engagement at a Catskills resort. In 1935, Warren auditioned successfully for the Radio City Music Hall Glee Club, joining future Metropolitan Opera colleagues, tenor Jan Peerce (already a featured soloist) and fellow baritone Robert Weede as a member of the chorus. It was during this period that Warren began to train with influential vocal coach, Sidney Deitch. In 1938, Warren became one of the finalists in the Metropolitan Opera Auditions of the Air competition, earning him prize money and an opportunity to formally audition for the company later that year.

Struck by the inherent quality of his voice, conductor Wilfred Pelletier took a personal interest in Warren's career development and helped to arrange for an additional stipend that would enable him to go to Italy for the summer to work on roles with teachers Giuseppe Pais and Riccardo Picozzi in preparation for a Metropolitan Opera debut in the fall of 1938. While staying in Milan, Warren struck up a friendship with two visiting New Yorkers, Agatha (or Agathe) Leifflen, a former voice student, and her brother Roy. Agatha would become Warren's wife a few years later, while her brother later served as Warren's legal advisor. Following his return to New York, Warren signed his first contract with the Metropolitan Opera Association on November 18, 1938. His initial appearance with the company was in a Sunday concert on November 27, 1938, in which he sang excerpts from and . His formal debut in a complete opera, in the role of Paolo in , came on January 13, 1939.

Still a somewhat raw talent, Warren's progress with the Metropolitan Opera was slow, but steady. Early on it was decided that the best course for him to pursue would be to focus on the Italian opera repertory. He became a Verdi specialist, most notably in the title role of . His performance was preserved in a 1950 landmark recording, the first complete opera released by RCA Victor. Warren enhanced his standing and broadened his experience through engagements in Argentina, Brazil, and Mexico during the 1940s. He also toured extensively throughout North America in recitals and regular appearances with other opera companies, including the San Francisco Opera.

His career seemed to coalesce most fully during the 1950s after he signed with the Sol Hurok organization in 1952. In 1953, he appeared to great acclaim in Milan, Italy at La Scala, winning over the Italian critics and audiences alike for his strong performances in the Verdi staples, and . The following year, Warren was intimately involved with the world premiere of Norman Dello Joio's cantata, . Another major accomplishment during this decade was Warren's 1958 tour of the Soviet Union, one of the first postwar appearances in that country by a prominent American performer.

Warren, who was steadfast in his preparation for his roles, developed a reputation for being difficult. His conversion to Catholicism also alienated some of his Jewish colleagues at the Metropolitan Opera. By the time the 1959-1960 opera season began, however, he was regarded as a fixture within the company and faced a demanding schedule. On March 4, 1960, while performing as Don Carlo in Verdi's , Warren collapsed onstage during the second act after completing the aria, "Urna fatale." Confusion ensued, the curtain was brought down, and Warren was pronounced dead backstage after attempts to administer oxygen and other forms of first aid failed; the apparent cause of his death was pronounced a cerebral hemorrhage. Declaring it, "one of the saddest nights in the history of the Metropolitan," general manager Rudolf Bing announced Warren's death to the stunned audience and suspended the rest of the performance.

Warren's death was treated as front page news in all of the New York papers. More than 3,000 people paid their respects at the Abbey funeral home, and the memorial service, held at the St. Vincent Ferrer Roman Catholic Church on March 7, 1960, was attended by over 1,000 mourners, including many of Warren's friends and associates. In 1986, the Leonard Warren Foundation was established by Barrett Crawford and Warren's sister, Vivien Warren, to promote the legacy of Leonard Warren and to provide support to young singers. In 2000, a Foundation-sponsored biography of the singer was published and a commemorative CD set of Warren's recordings was released.