Walter Henry Fisher was an English singer and actor of the Victorian era best remembered as the creator of the role of the Defendant in Gilbert and Sullivan's 1875 opera Trial by Jury. Beginning in the 1860s with much promise in comic plays, classics, Victorian burlesque, and as a versatile singer in opera and operetta, Fisher seemed headed for lasting stardom alongside his wife Lottie Venne. His career was limited, however, by his struggle with alcoholism, ending in the 1880s, and he died at age 44. Gustave Slapoffski described Fisher as "probably the finest comic opera tenor the English stage has ever known".

Trial by Jury is a comic opera in one act, with music by Arthur Sullivan and libretto by W. S. Gilbert. It was first produced on 25 March 1875, at London's Royalty Theatre, where it initially ran for 131 performances and was considered a hit, receiving critical praise and outrunning its popular companion piece, Jacques Offenbach's La Périchole. The story concerns a "breach of promise of marriage" lawsuit in which the judge and legal system are the objects of lighthearted satire. Gilbert based the libretto of Trial by Jury on an operetta parody that he had written in 1868.