Arthur Rackham
“Rackham’s technique was to sketch the outline of a drawing with a soft pencil, block in the various shapes surrounding his outline, and then add some of the details. Once he completed his pencil sketch he would add his lines in pen and India ink, removing the pencil lines at the end of the process. If the picture were to be in color, he would follow the same process after applying a light wash of color to the paper, and then add successive layers of color washes with transparent tints to finish the painting, a technique he essentially invented, and one which was well suited to photographic reproduction.” – Clarke Historical Library’s article on Arthur Rackham (that entire website’s really great)
More images here.