I have seen a great number of styles come and go, but the electric guitar has certainly produced a great number of them since it was introduced. Of course, I was not properly able to enjoy the style thanks to the -- ahem -- "dignity of the crown"... [Which, to be fair, Celestia understands. Perception is everything. It would be quite difficult for Equestria to reconcile the calm, serene Princess who raises the sun each day and guides them all with ageless wisdom with a hard-rocking Celestia neck deep in a mosh pit and letting her mane fly free. But that doesn't mean she has no regrets.] But -- well, ponies called it heavy metal at the time, though that term has expanded some as the genre has grown. I am not certain what humans might call it, if they even have it...