Swedish artist Andrée Wallin has quite the resume. Since getting into the business in 2008, he's provided concept art for games like Oblivion, Dirt 3, DJ Hero, Napoleon: Total War, MotorStorm and Split Second. Right now, he's working with 343 Industries on Halo 4.
He's also worked with clients like Universal Pictures and the Jim Henson Company, and in addition to concept art also produces production art and digital matte paintings.
Above you'll find a selection of his gaming art (along with some of the best of his other work), while his personal site has examples of loads more stuff.