17. RD-D2
Probably the most helpful character in the series, R2-D2 saves queen Amidala's ship from being destroyed, saves her again on Geonosis, carries the Death Star plans safely to Yavin IV, locates Princess Leia on the Death Star, saves Han, Luke and Leia from being crushed, helps Lando, Leia and Chewie escape from Cloud City and rebuilds C-3PO every time he gets blown up. RD-D2 comes with so many tools and is so useful in so many different situations that there's no doubt that whoever invented that type of droid is probably the Star Wars equivalent of Bill Gates. He is without question, the coolest droid in the Star Wars universe and the most loved silent movie character since Charlie Chaplin's little tramp.