The Imperial March is Vader's theme?

[TheDieselTrain]

As a life long fan I don't get why is this considered to be his theme.

I consider it to be the theme for The empire yet its widely considered to be his and his only.

Did it get that way because they (fans) wanted Darth Vader to have a theme. Did fans just decide its the bad guys theme so lets just say its his?

[Father Dougal McGuire]

I always associated Vader with this theme.... www.youtube.com/watch?v=5iUr7Q1Bhj4


Which I think is public domain since it was also in the Beavis And Butthead episode where they ruined Tom Anderson's lawn.

[Amazing Kitsune]

It is Darth Vader's theme. It's used almost primarily as such.

[Hassan bin Sober]

It's literally called "Darth Vader's Theme (Imperial March)". I don't think of it as his theme really though. He didn't have it in the first film and it was clearly being used as a theme for the Empire itself.