Bernard Herrmann (1911-1975) was one of the most popular and prolific composers of the mid-20th Century. His early work in radio was mostly for Orson Welles and the Mercury Theatre, and he moved to Hollywood to score Welles's debut Citizen Kane. But perhaps his most famous collaborations were with Alfred Hitchcock. he nearly scored all of Hitchcock's films between 1955 and 1964, including The Man Who Knew Too Much, North by Northwest, and Psycho. Some of the other films he worked on were Cape Fear and Taxi Driver.
One of my favorite scores, and also a great movie, is for Vertigo. I took the time to re-watch Vertigo the other week, and couldn't help but notice how Herrmann's theme played up the dreamlike nature of the film. A hard film to classify, I think everyone should see Vertigo at least once.
Here is Herrmann's main theme for Vertigo: