The Pink Panther Theme, written by Henry Mancini in 1964. Mancini had just garnered a bagful of Grammy and Oscar awards for his music for Breakfast at Tiffany's when The Pink Panther writer/director Blake Edwards approached him to join the project.
 
The resulting Panther music was almost as successful: three Grammys, an Oscar nod (though not an Oscar win), and over a year and a half riding on the charts. By sheer repetition, perhaps, the Theme (which is heard in all but one of the Edwards/Sellers Clousseau sequels and also in the cartoons), with its unforgettable da-dum da-dum -- or as the old joke goes, "dead ant, dead ant" -- introductory rhythm and suave sax solo, is the part most remembered from Mancini's score.
 
The other cues he provided, however, are hardly less wonderful, displaying Mancini's knack for veering with surprising alacrity between velvety 1960s lounge jazz, sleek European-style pop (pretty good for a guy born in Cleveland, OH, and raised in Pennsylvania), and occasionally, more traditional incidental music.