Today one of the best concept artist of all time, Ralph McQuarrie passed away. His work is his legacy. Rest in Peace Ralph.
When Star Wars still was a bunch of written dialogues and George Lucas was fighting with studio executives to make his cinematic vision come true. There appeared Ralph McQuarrie and made George's vision visible. The rest is history. The importance of a concept artist in the very first days of a project such as Star Wars is dramatically important. What those guys draw establish the atmosphere, the characters, the colors and the overall tone that the movie will likely had, if its ever done. Because those are the artists that start to work when there is almost nothing done yet, the ones that have to translate words into images for the first time, the ones that have to imagine it all.