Oscar Jimenez is a Spanish artist who had a great run on Flash - one of the best. His action sequences are second to none. His characters are tall and lean with exciting poses and proportions. He draws speeding effects better than anyone, and depicts musculature in motion amazingly. In his work, it really looks like the Flash is moving that quickly, as shown here. He also illustrates backgrounds well, with cool settings and details.
J. Scott Campbell
P. Craig Russell