This question was asked in the recent poll thread re Star Wars, esp. ep III.
So what’s the Straight Dope answer? Mine is - It was plenty cool enough when Frodo yelled “noooo” when Gandalf fell in the movie of “Fellowship of the Ring”
Any other cool ones, or was this an exception that proves the rule?
Marcel Marceau in Silent Movie.
I had completely forgotten about that.
And I think you’re absoutly correct.
well, technically, that was a simple “No!”
as opposed to the new cliched (i don’t know how to make the accent mark 
) NOOOOOOO! so often wailed in slow motion in any scene in which the main character witnesses a close friend/family member/cherished pet injured/slain by whatever evil s/he is fighting
Contains spoilers of Dead Poets Society and Once Were Warriors, you you haven’t seen those…
When the parents of the guy who killed himself found him in Dead Poets Society.
When the mother found the daughter hanged in Once Were Warriors.
I think they conveyed the emotions pretty successfully in those.
Do I need a spoiler for this? Hope not…
Buzz Lightyear does a similar “Noooooooooo!” after he learns that the Evil Emperor Zurg™ is his father, in “Toy Story 2.” It’s a nice shot… the elevator is going down the shaft, so Buzz recedes into the distance as he shouts in dismay.
Any time someone screams, “Noooooooooo” and then they get their head lopped off, that’s cool.
You can do good scenes with people shouting “no,” sure. I think doing anything good with the ‘fall to your knees and yell “NO” until your lungs give out’ thing would be very hard.
I prefere a minimalist approach…like in So I Married an Axe Murderer when the detective guy is pleading to commandeer a vehicle unfortunately being driven by Charles Grodin:
Charles Grodin: “No.”
When Luther was getting his just deserts at the end of The Warriors. That was a pretty memorable "NNNNnnnooooooooooooooo!!!..
I vote for Lois is dead from Superman the Movie – that was pretty cool and then he turned back time (was Cher watching?)
Spaceballs
Dark Helmet: If you do not give us the combination to your planet’s air shield, Doctor Scholtkin will give your daughter back… her old nose!
Princess Vespa: NOOOOOOOOOO!!!
Hell you don’t even have to go outside of the Star Wars franchise for a cool “Nooo!” scene: when Luke sees Obi-Wan get cut down by Darth Vader.
As noted upthread, there’s one way to make these scenes cool, and that is to dial them the hell down. Down so far, in fact, that there’s no words, let alone a whinge, coming out of the character’s mouth, and the actor does it all with his face and eyes. C.f. the first thing that came to my mind, Giles (Anthony Stewart Head) coming up the stairs in the Buffy the Vampire Slayer episode Passions.
–Cliffy
Not as cool if they did it after they get their heads lopped off.
William Shatner on “Invasion Iowa”, with a whole set of cue cards spelling out
NOOOOOOOO
OOOOOOOOO
OOOOOOOOO
etc.
Back to the Future had a good one:
Marty yells “Nooooo!” when he sees the Libyans gun down Doc Brown, hops into the DeLorean to escape, accidentally goes back in time, etc. When he returns to 1985, he runs to the parking lot but arrives too late, sees Doc Brown get shot again and is about to yell “Nooooo!” but is interrupted by his younger self, who he watches hop into DeLorean, accidentally go back in time, etc.
Or Chewie’s reaction in *Empire * when they close the doors, leaving Han and Luke outside to freeze.
I might be remembering it wrong, but I think there’s quite a good one in the first Matrix movie, uttered by Tank when Morpheus is captured.
nitpick: “Non.”
That wasn’t the Wookie howl for “No!” it was the Wookie howl for “Bastard still owes me five bucks!”