I have completed all the missions and have all the gold bricks. I already have Tarkin and Palpatine (and Savage Oppress for that matter). I'm at 99.4% and I'm hoping that between the missing character and vehicle I will get 100% because everything else has been bought or has all the green checkmarks.
You not only have to complete all the separatist missions you have to have Separtist status on the missions. The planets will be all in red letters. This should release the last character. (Moff Tarkin)
I am missing the first character in the the third row from the bottom. The character to the right is Onaconda Farr. I have already completed the rest of the game except for the seperatist/droid vehicle that ccm1022 has already asked about. I have wandered around both ships but have not found anyone that I have not bought.