Good topic, bigtyme! I've a few:

1. The entire Bespin showdown (Vader v. Skywalker), TESB, Dialogue esp.

I'd have to say this is where we really get a hint of the thoroughness that is Vader. Any "faceless" villian must be established by means other than sneers; Vader's lines are immortal! From "The Force is strong with you, young Skywalker...but you are not a Jedi, yet" all the way to "You are beaten. It is useless to resist", here is where we really get to see Vader at his masterful best. Don't get me wrong; in ANH, his throwing off of Kenobi's shackles with the line "when I left you, I was but the Learner; now I am the Master" and his snide "admonishment" of the unbelieving Imperial Officer ("I find your lack of faith..disturbing") had already done more than enough to entrench Vader in my psyche as truly..ill-tempered. But nearly every line he delivers in ESB can be classified as..classic. See his promotion of the Captain to Admiral in the space of a sentence during the asteroid field scene to remove any doubts.

**That's the first of a few discourses I've got up my tunic sleeve; lemmee know what you think. Thanks for lis'nin'.

Oh, does "The Clone Wars Vol I and II" count??

You are beaten. It is useless to resist.