Albums with a consistently-dark feel. Pic-related and Joy Division's 'Closer' come to mind.
This one, which is just as good as the ones you've mentioned
though parts of it are obscenely catchy
https://www.youtube.com/watch?v=SC6DvbEVHcI
You want just post-punk?
Nada!
Deathconsciousness
Boards of Canada absolutely terrify me
You don't know darkness
Any Katatonia album up to and including Night Is The New Day. Their last two are less "oppressively dark" and more "vaguely melancholy", kinda like staring into a dreary grey sky or something. But nah, their first 8 albums will sad your shit up and not give one iota of a fuck.
This is an obvious one though to me i'd describe it as being 'cold' instead of 'dark.'