I suspect it would be a certain type of classical music. Specifically, classical music that features lots of powerful heavy sounds, such as Beethoven's 5th symphony for example, rather than gentler music like Beethoven's 6th (the Pastoral) or Grief or Debussy.
I've heard it said that many heay metal and/or heavy rock fans also enjoy stuff like Beethoven, Mussorgsky and Wagner - especially Ride of the Valkyries.
indeed "they/ I do" but why Beethovens 5th only - take a look at the 9th 2nd set / the blueprint for millions of songs after.
The point is i think today lots of crossover projets were done with very interesting sounds. A lot of musicians are doing creativ things and I would never put them in one categorie. So why should we do that.
I like to be surprised by creative artists - never respect mistaken rules
see (hear) them playing live and get inspired / shocked / rocked / pushed
or whaterver music can do with us.
But music with no creativity is nothing I think
so be welcome and find out new inspirations for you and share them with us