With the Blu-ray release of the Star Wars movies, there was a lot of consternation regarding the small change at the end of Return of the Jedi, so that when Darth Vader finally decides to intercede on his son's behalf, thus killing the Emperor and turning back from the Dark Side of the Force, he now screams, "NOOOOO!" George Lucas has taken the usual amount of heat for this, but (a) the scene works OK with the scream, and (b) the scene is in good Star Wars tradition anyway.
What do I mean by this? Well, everybody knows that "I have a bad feeling about this" or various permutations thereof is a line heard in every Star Wars film. But you know what? So is "NOOOOO!". Here's a list of every Star Wars character who says or shouts "No!", and when.
The Phantom Menace:
Obi Wan Kenobi, when Qui Gon Jinn is struck down
Attack of the Clones:
Qui Gon Jinn, in spectral form, when Anakin slaughters the Sandpeople
Padme, when her decoy dies in the opening scene (said)
Revenge of the Sith:
Darth Vader, when he learns that Padme is dead
Palpatine, in defiance of Mace Windu (said and repeated)
A New Hope:
Luke Skywalker, when Obi Wan is struck down by Darth Vader
Princess Leia, as the Death Star prepares to destroy Alderaan (said)
C-3PO: when he hears that Luke and company are about to be squashed by the trash compactor
The Empire Strikes Back:
Luke Skywalker, when he learns that Darth Vader is his father
Luke Skywalker, earlier, in defiance to Vader (growled)
Han Solo, even earlier, when Chewbacca is putting wires in the wrong places on the Falcon. (said, but with Harrison Ford-ish emphasis)
Chewbacca, as Han is about to be put into carbon freeze (Well, OK, it's not like we get subtitles, but what else would he be howling?)
C-3PO: when hyperventilating during the asteroid field chase
Return of the Jedi:
Luke Skywalker, when Darth Vader insinuates that maybe Leia will turn to the Dark Side
Darth Vader, when he realizes that Palpatine is really something of a douche.
How many am I missing, Star Warriors?