sound played when a key character appears

What is the name for the music or sound played when a key character appears in a play, movie or show; like in "Peter and the Wolf"?

Solution 1:

I think the word you're looking for is leitmotif:

A recurrent theme throughout a musical or literary composition, associated with a particular person, idea, or situation.

[ODO]

Solution 2:

The tune associated with a particular character is called that character's musical theme, theme music, or signature song.

From the Wikipedia article on Peter and the Wolf, for example:

Each character in the story has a particular instrument and a musical theme:

Bird: flute
Cat: clarinet
Duck: oboe
Grandfather: bassoon
Hunters: woodwind theme, with gunshots on timpani and bass drum
Peter: instruments (including violin, viola, cello, and bass)
Wolf: French horns

And similarly, quoting from the Wikipedia article on "theme music":

The phrase theme song or signature tune may also be used to refer to a signature song that has become especially associated with a particular performer or dignitary; often used as they make an entrance.

Solution 3:

I think I may have found it: "leitmotif."

From the Wikipedia entry a leitmotif is "is a "short, constantly recurring musical phrase" associated with a particular person, place, or idea."

Solution 4:

Although several answers have identified "leitmotif," if the music in question is more brief it could be called a

fanfare

or

flourish

OED describes a fanfare as:

A short ceremonial tune or flourish played on brass instruments, typically to introduce something or someone important: a specially composed fanfare announced the arrival of the Duchess

The relevant definition for flourish cites "fanfare" but another definition provides color:

A bold or extravagant gesture or action, made especially to attract attention: with a flourish, she ushered them inside