3. Yoda - Star Wars Episode V: The Empire Strikes Back
Yoda is in many ways the prototypical sequel character given that, when the threat of the Empire looms, he is the Master Jedi who trains Luke Skywalker, to prepare him for the inevitable showdown against Darth Vader (even if it doesn't quite go as Luke expected, due to Luke's impatience). Yoda is the ultimate sage, old, wise guy, a creature who is impossibly knowledgeable and should be listened to at all times, given how right he proves to be throughout The Empire Strikes Back.
Best Moment: Easily the character's most memorable line comes when Yoda tells Luke, "Try not. Do... or do not. There is no try." It's a line that totally encompasses Yoda's school of thought throughout these films. Yoda goes on to die peacefully in Return of the Jedi, though lives on through George Lucas' ropey prequel trilogy (I guess).