William Claude Rains (10 November 1889–30 May 1967) was an English stage and film actor whose career spanned 47 years; he later held American citizenship. He was known for many roles in Hollywood films, among them the voice of The Invisible Man, the corrupt senator in Mr. Smith Goes to Washington, and perhaps his most-famous performance, the amoral Captain Renault in Casablanca.

Rains was born in Camberwell, London on November 10, 1889. He grew up, according to his daughter, with "a very serious cockney accent and a speech impediment".

His acting talents were recognised by Sir Herbert Beerbohm Tree, founder of The Royal Academy of Dramatic Art. Tree paid for the elocution lessons Rains needed in order to succeed as an actor. Later, Rains taught at the institution, teaching John Gielgud and Laurence Olivier, among others.