KojiChao
From Sonic Retro
Kojichao is one of the most respected artists in the scene, was hired once to draw Sonic art for a games magazine almost indistinguishable from the original style. Also did much of the graphic design for Sonic CulT.
Also an oldbie of the Sonic Community, dating back to the original Area 51.
External link
Her art can be found at: http://kojichan.deviantart.com/
Her personal website, including her newer work, can be found at: http://kojichan.neosouthisland.com/