essentials; these are the recordings widely agreed upon as classics, though will a little of my personal taste interjected. familiarity with these will allow you to more easily determine what else is worth listening to and what's derivative crap;
immortal - pure holocaust
burzum - burzum/aske, det som engang var, hvis lyset tar oss, filosofem
darkthrone - transilvanian hunger, panzerfaust, under a funeral moon (how was i the first person to mention them?!)
bathory - under the sign of the black mark, blood fire death
enslaved - vikinglgr veldi
mayhem - live in leipzig, de mysteriis dom sathanas
emperor - in the nightside eclipse
gorgoroth - antichrist
ulver - bergtatt (controversial one here...)
graveland - thousand swords (personally can't understand what people see in this one, but it's accalimed enough that you should at least check it out)
summoning - dol guldur
beherit - drawing down the moon
necromantia - scarlet evil witching black
varathron - his majesty at the swamp
some more recent/less classic stuff
nokturnal mortum - goat horns, lunar poetry (all their albums are pretty good as far as i know)
deathspell omega - si monumentum requires circumspice
drudkh - autumn aurora, forgotten legends, the swan road
mutiilation - remains of a dead ruined cursed soul, vampires of black imperial blood
vlad tepes/belketre - march to the black holocaust (split)
alcest - le secret
nocternity - onyx
krieg - the black house, patrick bateman
antaeus - cut your flesh and worship satan
moonblood - blut and krieg
blut aus nord - the work which transform god (it's now become trendy to hate this album, but oh well. their earlier stuff is apparently good too)
velvet cacoon - genevieve
graveland - memory and destiny, the fire of awakening, dawn of iron blades (this era of stuff is far superior to his supposed "classic" material, imo)
demoncy - joined in darkness (some people absolutely love this, personally i think it's pretty good but am yet to hear in it what they hear....still trying, though)
gontyna kry - welowie
there's more, but i'm not going to make a huge list of bands. i don't think i've omitted anything of undeniably high quality.
edit: i definitely advise downloading before buying with black metal
