I think St. Vitus made a pretty good list!
That list doesn't include any of my favorites though. My favorites in extreme metal (which rules out Type O Negative, Guns N' Roses, 3rd & The Mortal, Theatre of Tragedy & Iron Maiden), are:
Opeth: Blackwater park
Burzum: Hvis lyset tar oss
Satyricon: The Shadowthrone
Satyricon: Nemesis Divina
(Machine Head: Burn my eyes) - I don't know if this qualifies...?
Mayhem: De Mysteriis dom Sathanas
Dimmu Borgir: Enthrone Darkness Triumphant
Opeth: My arms your hearse
Emperor: IX Equilibrium
Emperor: In the nighside eclipse
Limbonic Art: Moon in the Scorpio
(Pantera Far beyond driven) - I don't know if this qualifies either...?
Burzum: Det som engang var
Thorns: Thorns
Arturus: "Aspera Hiems Symfonia"
I wouldn't say any of these are any of the most influencial extreme metal albums of all time though. I don't think you could ask a black metal band their inspirations and they would say Dimmu Borgir's "Enthrone Darkness triumphant" and get as many "votes" on that, as you would get on Bathory, Venom & Destruction. The albums I mentioned wasn't exactly something new when they came out.
I also think MacMoney has a good point in "How can something be most influential if it hasn't been even 10 years from its release?"