Dio! What can you say, other than, "Duuuude, that guy can holler?"
Okay, you could probably say other stuff, but still. He could holler.
He also supposedly invented the devil-horn hand symbol thing as the universal hand-rock signage, which is pretty cool, and will earn him forgiveness (from me at least) for using that dumb-ass synth line in "Rainbow in the Dark."
And just in case you have no clue who or what I'm talking about, here's this: