神谷浩史
He`s done too many things to list, so look him up.
and
関 智一, who has also done a freaking huge list of stuff.
Because they`re just very *good*. Most of the voice actors are fairly easy to tell. My husband, who went to a school for seiyuu (but never graduated because he didn`t have enough money, and his parents were utterly appalled by the idea of him pursuing that career so wouldn`t help... *sigh*) can usually tell who *any* seiyuu is just by hearing a few lines. But these two are very good at being the character, and have very flexible voices, so is harder to tell. Which is a sign of being really good.
My husband has another favorite who he sort of looks up every once in a while to see what he`s doing... But for the life of me I can`t remember his name.
Female seiyuu, for some reason only linger in my mind if I find them irritating...