I agree with Drudkh. Excellent suggestion.
Katatonia - Brave Murder Day
Amorphis - The Karelian Isthmus
In Flames - The Jester Race
Agalloch - Pale Folklore
Dissection - The Somberlain
They'd be pretty good intro albums for darker death metal / black metal, but still quite melodic and accessable.
Aeternus, I don't think is a good intro, neither are Burzum or Graveland. IF you wanted to go down a more extreme black metal sound, I'd go with Deathspell Omega.