Billion Dollar Brain is a 1967 British espionage film directed by Ken Russell and based on the 1966 novel Billion-Dollar Brain by Len Deighton. The film features Michael Caine as secret agent Harry Palmer, the anti-hero protagonist. The "brain" of the title is a sophisticated computer with which an anti-communist organisation controls its worldwide anti-Soviet spy network.

Henry Kenneth Alfred Russell was a British film director, known for his pioneering work in television and film and for his flamboyant and controversial style. His films were mainly liberal adaptations of existing texts, or biographies, notably of composers of the Romantic era. Russell began directing for the BBC, where he made creative adaptations of composers' lives which were unusual for the time. He also directed many feature films independently and for studios.