Brutal

I like all of the sub-genres I posted in the description, but my favorite has to be Death Metal, here are some of what I consider to be the best songs of the genre.

Amon Amarth- Twilight Of The Thunder God.
These guys are just bad ass Vikings singing (growling) about bad ass Viking stuff.
http://www.youtube.com/watch?v=edBYB1VCV0k

Cannibal Corpse- Hammer Smashed Face.
As you can tell by the band name and especially the song name, cc are not for the feint-hearted (to put it this way you will be glad you cant hear what he is saying). Very brutal and what most DeathHeads would consider the holy hymn of death metal.
http://www.youtube.com/watch?v=gNhN6lT-y5U

Deicide- Lunatic Of Gods Creation.
'Deicide' literally meaning the death of god are a very blasphemous band and are proud of being so, the lead singer even has an inverted cross branded into his forehead. The bands music, in this album (there debut self titled) especially is very raw and hard to listen to if you haven't listened to death metal before.
http://www.youtube.com/watch?v=MPvRBiQY6lo

Dy*** Fe***- K*** your M*****/ R*** your D**
As you can tell everything about this band is extremely offensive. Although I had to put them in as they are pretty much the innovators of the extreme U.S side of Death metal, which has escalated into (sub?)sub-genres of Death metal such as brutal slam, the song titles and band names have also escalated in offensiveness.
Here's the link, and as I have said this band is very offensive (you've been warned)
http://www.youtube.com/watch?v=wqOJD_TdIKY

Nile- Lashed to the Slave Stick.
Nile are very unique in what they sing about- Egyptians. With eerie sound affects, traditional Egyptian instruments and epic song lengths Nile are perhaps one of the most talented Death metal bands, it is also the band of my favorite drummer, George Kollias.
http://www.youtube.com/watch?v=ZD3dimKaJtA

Dethklok- Murmaider
Cartoon band from Tv- series 'Metalocalypse', as well as being a good band they are also humorous (being derived from a cartoon band).
"this song is about mermaids, and murder, it's called murmaid... er"- Nathan Explosion (lead singer).
http://www.youtube.com/watch?v=30Rk1gjtK68