I actually think one of the defining characteristics of metal (aesthetically) is an easily identifiable logo (either because it's so easy to read and original or because of its INABILITY to be properly read, heh).
A few:
Vomit Remnants
Insidious Decrepancy
Spawn Of Possession
Ugh how could I forget Cephalotripsy's...I love it:
I always found Demilich's to be a little misleading because just by the logo, I would think they played folk metal or something because the logo looks like leaves or twigs er something