For some REALLY scary things, check the following:
LUSTMORD: Monstruous soul
BOYD RICE AND FRIENDS: Music, Martinis and Mysanthopy
CURRENT 93: early stuff, notably Dogs Blood Rising on LAYLAH rec. (a lot
of stuff on that label is dark)
Some of the early HAFLER TRIO also, or even Throbbing Gristtle.
If you want more, ask, I could do a more thorough search.
Alain M.