Everyone thinks Vader's an ENTJ- but I beg to differ..
Look at his past, and really analyze him. After seeing the most recent episode I think it safe to infer that he may be ENFJ or ENFP- he would have done anything for his wife and baby- and took revenge for them- something I think an F would be more prone to do.
I could be way off, but I don't think it's as obvious as ENTJ, just doesn't work like that- you can't just assume he's one if he's an evil dictator. You've gotta look into him and understand where he's coming from- and you'll understand.
Let's just say I'm open to anything except INTJ or ENTJ- it seems to obvious, and my brain works that way.
Is it that by its indefiniteness it shadows forth the heartless voids and immensities of the universe, and thus stabs us from behind with the thought of annihilation, when beholding the white depths of the milky way?
Erm, I think it's because C-3P0 is programmed for ISFJ tasks. ESFJ being the second possibility.
In Star Wars Universe, protocolar droids are ISFJ and droids astromechano are ESTP, in our universe, computers are ISTJ. The common point is every machine have sensing in dominant fuction and intuition in inferior. Machines can't have intuition.
And if you want to get technical, Anakin is an ENFP in The Phantom Menace and an ESTP in Attack of the Clones, and I'm not really sure about Revenge of the Sith.
Anakin is always ENFP (except as Vader of course), even if in the episode III, he've developped is tertiary function Te and looks a little ENTP/ENTJ. (Oh, and I could never admit that an ESTP could be as Silly as the Anakin of the Episode II...)
Qui-Gon was the most INJ Jedi in the council -- seeing how he foresaw beyond everyone else.
Qui-Gon is definitely an F, maybe INFJ, but he lives above all in the present moment, so he's ISFJ. I think the most INJ Jedi in the council is Yarael Poof (INTJ), there's maybe Oppo Rancisis, but I think is rather ENFJ.