Because Star Wars has a very expansive universe and the relationships between characters are rather complex, I have decided that it would be best to keep my poster design relatively simple, in order to focus on aesthetics rather than worrying too much about intricate details.
My poster idea is to pick the top 8 characters that best represent the Rebel Alliance (Luke, Leia, Han Solo, C-3PO, R2-D2, Obi Wan, Yoda, Chewbacca) and 8 characters that represent the Galactic Empire (Darth Vader, Emperor Palpatine, General Tarkin, Admiral Piet, Storm Troopers, Scout Troopers, Boba Fett, Imperial Royal Guard), and represent them on each side of the poster, showing who are the ‘bad guys’ and who are the ‘good guys’, and also showing their rank within their respective circles.
I made this mockup on Photoshop so I could figure out the layout easily and find a way of presenting the images that was informative and visually appealing. I think this design works best, as it clearly communicates the hierarchy of the Empire. I may change the colour of the concentric circles in the final design, because, although the initial idea was to emulate the colour of the Sith lightsaber, I think that the red glow looks messy and out of place with the rest of the image.