Not sure how many have been mentioned (and some aren't really metal) but:

Slayer, Iron Maiden, Primus, Napalm Death, Cannibal Corpse, Cancer, Lawnmower Deth, Ozzy, Black Sabbath, System of a down, Rollins band, Overkill, Motorhead, Exodus, White Zombie, Carcass, Wednesday 13 and loads i've forgotten