Here comes a doozy!
I present to you Devourment. They're the first band that comes to my mind when the word 'brutal' pops into my head. They are one of the first bands to play an especially catchy form of brutal death metal called 'slam', which is a barrel of breakdowns and blasts, plus some of the most guttural vocals ever laid to tape. I will admit that they're a bit of a hard listen at first (the poor production quality on their earlier releases has something to do with this) but if you're willing to get past this, you're in for quite a fun ride!
[youtube]http://www.youtube.com/watch?v=pKmfbhxYj2s[/youtube]
Up next is Darkspace. One of the most unique acts in the black metal underground, and in metal overall! Darkspace is a rarity by the means of their being a black metal band that doesn't make any mention of Satan, burning down churches, misanthropy or anything of the like in their lyrics. In fact, more often than not, their songs are instrumentals. Their music is ambient, atmospheric, totally evil-sounding, lo-fi and and at times can be quite brutal. Subtle but ever-present keyboard lines characterize and intensify the already heavy music. All of their material is amazing, but this track, in my opinion at least, is their absolute magnum opus. Skip to 6:50 for an absolute interstellar conquest.
[youtube]http://www.youtube.com/watch?v=7rwt_UjLPrk[/youtube]
Here is Sweden's own Shining. (Note: not 'The' Shining, just 'Shining'. Also, I make the note of them being from Sweden to distinguish them from another Shining, a Norwegian progressive jazz outfit.) They are the pioneers of a particularly 'kvlt' branch of black metal known as Depressive Suicidal Black Metal, or DSBM. However, only their earlier material, in my opinion, (the first three albums) can be classified as such. From their fourth album onward, they made a name for themselves thanks to their long-winded and multi-layered brand of progressive black metal. This music is compelling, melancholic, heavy and often has acoustic portions. Make no mistake, Niklas Kvarforth is a demented genius, and is undeniably the driving creative force behind Shining. Here's one of my favorite songs of theirs.
[youtube]http://www.youtube.com/watch?v=gs2vNvMljRg[/youtube]
And now for something completely different, and not even metal at all: Arditi. Arditi is perhaps most well known for their two collaboration tracks with the Swedish black metal band Marduk. Although I enjoy those songs, I find that they're a poor representative of the kind of music that Arditi plays: martial industrial. This is a highly varied and very underground movement which draws creative influence from classical, ambient war marches, industrial, choral and acoustic. (In all honesty, they could easily pass for the soundtrack to a war movie.) Arditi crafts a compelling and positively militant breed of music that I consider to be brutal (and, in turn, am presenting to you) because it is indeed so in spirit and essence. This track of theirs has groovy and terrifying percussion, which I revel in.
[youtube]http://www.youtube.com/watch?v=cJJsTQw65_I[/youtube]
Hope you enjoy!