Arsen said:
Classic Metal
Power Metal
Thrash Metal
Speed Metal
Death Metal
Black Metal
Viking Metal
Melodic [insert genre here] Metal
...
If it can't fit into any of those categories, or what was inspired by those categories...it ISN'T metal. It's made to sell.
For fuck's sake, there is no such thing as Viking metal. There are lots of metal bands that sing about Vikings, sure, but "Viking metal" is not a styliscally separate kind of metal. Black metal bands sing about Vikings. Power metal bands sing about Vikings.
Also, you forgot doom metal. Which, I guess could arguably be "classic" metal, even though there's no such thing as that, either. In the beginning of metal music, back in the late sixties, Black Sabbath inspired and defined doom metal, bands like Steppenwolf and Deep Purple defined and inspired traditional heavy metal, and other styles like death, black and thrash metal came later in the 70s and 80s with the advent of punk rock and hardcore punk. Power metal is largely rooted with the New Wave of British Heavy Metal (NWoBHM) movement, the most notable of whose artists include Helloween, Diamond Head, Crimson Glory, Iron Maiden, etc.
Punk fans down on metal all the time for being too heavy and too complex and metalheads down on punk all the time for being too simple and in the end the two genres are highly dependent on each other and at times aren't even all that different. Listen to very early thrash metal albums and you'll hear that it's pretty much hardcore punk with more guitar solos.
Even "speed metal" is a stretch because pretty much every metal act I've heard referred to as speed metal would be easier to just call thrash or power metal. Most metal involves some sense of speed, so why be redundant?
And as far as false metal goes, bullshit like Theory of a Deadman and Nickelback and Shinedown, or worse yet, moving from post-grunge shitland to deathcore cockshining, you have bands like Bring Me the Horizon with their "brutality." I didn't know high school kids spending mommy and daddy's money so they can play the same chug riffs over and over on nice sound equipment constituted brutality.