William L. Lewis (born November 23, 1931, Tulsa, Oklahoma) is an American operatic tenor and academic.
William Lewis was educated at the University of Colorado, Texas Christian University and New York University. He began his career as a writer and an athlete before deciding to pursue a career in opera. He began his voice training under Karl Kritz and Arthur Faguy Coté in Fort Worth, followed by studies with Susan Seton and Hulda and Luigi Rossini in New York. He made his professional opera debut in 1953 with Fort Worth Opera as Rinuccio in Puccini's Gianni Schicchi. Two years later he won the Metropolitan Opera's Audition of the Air competition (precursor to the National Council Auditions). Lewis made his debut at the Metropolitan Opera as Narraboth in Salome on March 1, 1958 and subsequently sang in 234 performances in his 35 years with the company. In 1975 he made his debut at San Francisco Opera as Steuermann and Erik in The Flying Dutchman and has sung in sixteen different productions with the company in subsequent seasons. In 1981 he made his debut at the Salzburg Festival in the title role of Offenbach's The Tales of Hoffmann, returning there for the following four years in such roles as Arbace in Idomeneo and the First Geharnischter in The Magic Flute. In 1990 he made his debut at the Teatro Lirico in the world premiere of Azio Corghi's Blimunda.