Here's conceptual art of Franco as the Wizard:
Plus, Mila Kunis has been casted as Theodora, the
eventual Wicked Witch of the West. No, she won't have green skin. Theodora is described as beautiful, dressed in an open-collared white shirt, black pants, and black knee-high boots with “quick eyes, quick movements, and a quick, lively mind.”:
http://www.newsinfilm.com/2011/02/17...in-oz-prequel/