Mario Sereni was an Italian baritone, who sang leading roles at the New York Metropolitan Opera for many years.
Sereni was born in Perugia, Italy. He attended the Accademia di Santa Cecilia in Rome and the Accademia Chigiana in Siena where he was a pupil of Mario Basiola. His professional career began in 1953, at the Maggio Musicale Fiorentino and within four years he made his debut at the Metropolitan Opera on 9 November 1957 as Gérard in Andrea Chénier.
Sereni enjoyed a long and steady career at the Metropolitan Opera. In twenty-seven seasons, he sang most of the important baritone roles of the Italian repertory in operas such as Ernani, Luisa Miller, Il trovatore, La traviata, Un ballo in maschera, La forza del destino, Don Carlo, and Aida. He also sang in La Gioconda, Cavalleria rusticana, Manon Lescaut, La bohème, and Madama Butterfly, as well as L'elisir d'amore and Lucia di Lammermoor.
Sereni was also a regular guest at the opera houses of Chicago, San Francisco and Dallas. He also enjoyed a successful international career appearing frequently at the Vienna State Opera, La Scala in Milan and the Teatro Colón in Buenos Aires.