I took a look at the compilation '' Let's die'' by Mystic Records because I heard it was a collection of early Deathrock, Punk and even some Metal

As for metal/goth fusions? well first of we have the doomy A.W.O.L with Hellhouse: http://www.youtube.com/watch?v=p7hDRdhq4-w
And also Burning Image. This is another song by them, check out the totally metal cover art: http://www.youtube.com/watch?v=VCAZMMx7VcY
Other than that there is the pretty heavy Slaughterhouse 5 though they don't really play Metal but the mood they set remind me a bit of Sarcofagus or Icecross. And Silver Chalice that play 70's inspired glam punk/rock.
I also got wind of Creaming Jesus who I saw mentioned as a thrash/goth hybrid. But their first LP is basically Hardcore without that much thrash or goth influences. Their followup fares a bit better with some Thrash riffs and a more dark atmosphere and gothic vocals. http://www.youtube.com/watch?v=6oeBm2DnWvE
There's also even more quasi-metal from Eva O (Super Heroines, Christian Death) and Rozz Williams ( Christian Death) under the name 'Shadow Project' Here is a sample of their first album: http://www.youtube.com/watch?v=8tokUmuWRU4
And from their second: http://www.youtube.com/watch?v=s9o81b3UtdM the cover art here really makes me think 90's Katatonia/ My Dying Bride