American bass-baritone Thomas Stewart was born on 29 August 1928 in San Saba, Texas. He graduated from Juilliard where he met and married soprano Evelyn Lear. In 1954 he made his professional début at the Chicago Lyric Opera. He received a Fullbright scholarship to study in Germany and in 1958 he débuted at the Deutsche Oper Berlin.
In 1966 he made his New York Metropolitan Opera début and proceeded to sing the major Wagner baritone roles there, as well as other parts including: Mozart's Don Giovanni, Ford in Verdi's Falstaff, the Villains in Offenbach's Tales of Hoffman, Orest in Strauss's Elektra and Jokanaan in the same composer's Salomé.
Stewart sang at the Wagner Festival in Bayreuth for thirteen seasons and performed Wagner's Ring at Buenos Aires, Vienna, Hamburg, Berlin, Paris, San Francisco and the Met in New York. Known particulsrly for his Wagner roles, he had a very wide-ranging repertoire and, for example, created the roles Dioneo in The Visitors by Carlos Chávez and Jupiter in Giselher Klebe's opera Alkmene.
The couple founded and ran the Evelyn Lear and Thomas Stewart Emerging Singers Program, helping Wagnerian singers early in their careers by giving them exposure through performances and furthering their vocal education. They generously donated their time and influence to the Wagner Society of Washington DC in order to make this program a success. The program sponsored multiple concerts and helped a number of young singers. The Stewarts coached these singers and frequently contacted opera directors in Europe to secure positions for them.
Thomas Stewart died suddenly on 24 September 2006, aged seventy-eight, whilst playing golf with his wife near their home in Rockville, Maryland.