In an interview with with Reece Reilly for the Kiwi Talkz YouTube channel, former WWE composer Jim Johnston talked about writing the music for The Undertaker:
“Undertaker is simple but there’s also a complexity to it as well. It isn’t like it’s really, complex cord changes; it’s just simple in E minor. It’s a nursery rhyme, really, in how I wrote it because it’s the only thing I could figure out it sounded like… I was gonna say that it’s the only thing that sounds like death, but it doesn’t really sound like death. To me, it sounds more like sorrow, and I always found that was an interesting part of how I saw Undertaker’s character. We don’t know what happened to this guy or how he got here, but it probably was not all good. There was probably some sad stuff that happened to him.
So when I did this nursery rhyme thing, it just fit for some reason. I think there is a really strong parallel with the Star Wars theme. There’s an incredibly fine line in that kind of stuff between, ‘Boy, does this work! This is great!’ And, ‘This is absolutely laughable!’ It’s like, ‘We’re supposed to believe this guy is dead because he wears a long, black, leather jacket? How stupid do you think we are?’ I think about it in the same light as Darth Vader. It completely works yet the guy in the suit is not even Darth Vader. It’s a different voice and a different guy.”
(quote courtesy of WrestlingInc.com)
