Here is the Vancouver Symphony (being conducted by Bramwell Tovey) playing the famous Imperial March from the movie Star Wars, composed by one of the most famous and prolific film composers, John Williams.
This "Darth Vader theme" is an excellent example of how a composer can use music to make the character more real - Darth Vader not just looks evil with the black robot helmet and cape, but sounds evil, powerful, and destructive.
Power is provided by a symphony orchestra - one hundred musicians playing forte
Evil-sounding - the minor key of the piece sounds ominous and dark
There is no question, Darth Vader is a bad guy. Just in case you've never seen the very first, original Star Wars (1977), here is a great montage of Darth Vader using the Imperial March.