Since we have an omniscent point of view, we get to know everything's that's going on in the films apart from what the character's are thinking. However, in universe, nobody seems to know the whole story. It seems Palpatine knows the most since he's aware of all the diabolical behind-the-scenes political manipulations he's been up to, and by the end, he learns that Anakin's son survived and that Padme had a second child, though it's not clear he's ever met her or that he knows her name is Leia or that she's been raised by Bail Organa. Unless he used to Force to see them, he's also pretty much unaware of who Han Solo is, except that he played a part in destroying the 1st Death Star, or who Lando is, or that Jabba received Solo's carbonite encased body. Still, he seems like a good candidate for the character who knows the most. On the good guy side, they seem to know a lot less. By the end of ROTS, Yoda and Obi-Wan seem to know that Palpatine is behind the war, but do they know that Dooku was working together with Palpatine to stage the war? Do they know that Dooku was Palpatine's apprentice or did they merely think that Dooku is a fallen Jedi and believe that he was actually opposed to Palpatine all along? Do they ever figure out that Palpatine was behind the Naboo/Trade Federation crisis or the creation of the clones? Then, when you get to the OT, what "new" character there knows the most about the entire saga by the end? Luke? Leia? Artoo?