We've probably done this before, but who cares?
Just to be clear, we're not interested in the covers of your favourite games, only your favourite artwork. Sometimes you might like an artwork BECAUSE you like the game, which is understandable, but try to focus solely on the art itself. My favourite ever has always (well, since 1995 anyway) been this one:
WITCHAVEN II: BLOOD VENGEANCE
So freakin' metal. Looks like it might be one of Frank Frazetta's paintings. Anyone know if that's the case? I've never actually played the game, though!