Heavy metal really falls into two camps. Those who like the "power" aspect of it treat it as basically a "purification" of Rock's original ideals (before "those damn Brits ruined it all"), where it has the same general tone but a much harder edge than, say, The Rolling Stones. Often overlaps with the "hard rock" genre. Regular heavy metal and glam metal fall under this. But then you get into the "extreme" forms of metal, which tend more towards "darker" themes and more distorted sounds. The latter camp is especially popular in the portrayal of Darker and Edgier, where it is a popular genre for vampires, demons and other Ax-Crazy character types to enjoy. It's tendency towards Heavy Mithril and growling vocals often make it the target of parody, though.