Smug One is a British street artist who creates incredibly realistic yet highly stylized graffiti paintings. He creates some incredibly beautiful work of women, famous character portraits, and bizarre/humorous scenes. You can check out a large gallery of his work on Flickr.
Alexandre Farto aka Vhils is a Portuguese street artist based in London. He has an amazing knack for creating large wall art pieces. His art stands out because they huge pieces that are created by playing with layers and textures to create the effect.