Perhaps the best known Star Wars concept artist is Ralph McQuarrie, responsible for creating the artwork that guided the look of the first three Star Wars films. Doug Chiang was Art Director for both episodes I and II, while Peter Russell was the Supervising Art Director for episode III.
Ralph McQuarrie was first approached by George Lucas in the early '70s, when Lucas initially pitched the idea for the first Star Wars film to him. Starting in 1975, McQuarrie eventually created 21 paintings depicting several scenes in the story, as well as several now-iconic Star Wars characters, including the 'droids R2-D2 &; C-3PO, the Wookie Chewbacca and the main villain, Darth Vader. His other designs included the Millennium Falcon, the rebel X-Wing fighter, the Imperial TIE fighter and an early version of the Death Star.
Mr. McQuarrie was George Lucas' first choice as Art Director for Episode I: The Phantom Menace, but McQuarrie turned the job down, feeling he was past his prime. Doug Chiang of Industrial Light and Magic was brought on board as Art Director in 1994. He stayed with the franchise for the next film, Attack of the Clones, as well.
By Episode III: Revenge of the Sith, the responsibility for art direction was split between four Art Directors; Ian Gracie, Phil Harvey, David Lee and Peter Russell, with Russell acting as Supervising Art Director.