Old school Doom

So because of my interest in Stoner Doom, I've found my self trailing to the origins of the genre and came across Pentagram. I already knew of Black Sabbath ofcourse, and I also enjoy some St. Vitus...
So, I was wondering if any of ya'll could help me with older doom...stuff is the shit and I wanna hear some more.

 

Sleep

 

Doesn't get older than Pentagram and Black Sabbath! Pentagram is a fantastic band, by the way :cheers2:

 

Witchfinder General
Trouble
Cirith Ungol (hope I spelled it right)
Death Row (Pentagram with another name)
Bedemon, an even "doomier" Pentagram side project.
Count Raven
The Obsessed

 

Cathedral
Anathema

 

Burning witch

^not really 'old school' doom, but is very slow and grungy, raw doom