The Avengers (1961)

This is the 1960s spy series, not the Marvel films. The early episodes used a jazzy theme by John Dankworth, but the one everyone remembers is Laurie Johnson's, introduced in 1965 when Diana Rigg joined as Emma Peel. Johnson built it from an earlier track of his called The Shake, and you can hear the dance floor in it: a brassy, strutting fanfare with a swinging rhythm that is pure mid-sixties London. It is as stylish and faintly ridiculous as Steed's bowler hat, which is exactly why it works.