William Castle (22 December 1836 — 31 March 1909)[1] was an English tenor who was active mainly in the United States during the mid to late 19th century.

Historian Kurt Gänzl described Castle as the "most popular operatic tenor of the Victorian era on the English-language stages of America".

Also at that theater in 1864, he portrayed Manuel in the United States premiere of Michael William Balfe's The Rose of Castille.

He appeared in several more Broadway productions during his career, including portrayals of the Lorenzo in Fra Diavolo (1864 and 1867), Thaddeus in The Bohemian Girl (1864 and 1867), and Captain Maurice in The Desert Flower (1868).

After a long absence, he returned to Broadway in 1886 to star as Sándor Barinkay in the United States premiere of Johann Strauss II's The Gypsy Baron at the Casino Theatre.