Alot of the great albums have been listed already but how about these:
Hypocrisy - Abducted, they never got better than this
Deicide - Legion, like no other Deicide album; actually brutal
Carcass - Necroticism, super-creative riff-o-mania
Entombed - Clandestine, before the 'death and roll' crud
Nocturnus - The Key, one of the first technical brutal death albums