Karol Kolodzinski is an extremely talented digital artist, illustrater and art director based out of Warsaw, Poland. She's worked on some very impressive clients such as Avatar the Game, Nike, Bacardi and more. Her work is also wide ranging from ads, to websites, to illustrations and motion capture movies. Check out more of her impressive work on Behance.
Erik Schumacher (kire1987 on Deviant Art) is a German student studying physics, but in my opinion, he should stick to art. He definitely has some impressive work and is part of the distinguished Depthcore art collective. There is a distinct style to his work, but his techniques don't feel overused. Check out some more of his work on Deviant Art.