Disturbing metal

Khanate
Bethlehem

I can't get into Khanate at all. In fact, I can't really make it through a song of theirs.

As for Bethlehem, I've been meaning to check out Sardonischer Untergang Im Zeichen Irreligiöser Darbietung. I read a review on it not too long ago. Sounds like something I might be interested in.
 
Pig Destroyer (The sample used in "Gravedancer" is pretty fucking disturbing.)

I have not heard that particular song but some of their songs are unsettling.

(Some) Fantomas
(Some) Entombed - like the song "In The Flesh" is one of their creepiest songs.
Sepultura - Schizophrenia (whole album)