Not sure if this is the right order, but . . .
Opeth - Morningrise
The epitome of music for me. Heavy, mellow, emotional, raw. This album's got it all.
Metallica - ... And Justice for All
My "real music" gateway. Before this I listened to nothing but Red Hot Chili Peppers and Pearl Jam. I love this band, every one of their releases, even the new ones.
Katatonia - Brave Murder Day
The darkest, most depressing album ever.
Dark Tranquillity - Haven
The album that got me into death metal, and still an all-time favorite.
The Crown - Deathrace King
Brutal, thrashy, excellent.