Since GI Joe Reloaded was a far more serious take on GI Joe, I think it -along with teh Marvel run of GI Joe should've been considered as the basis for a movie. As the upcoming film will mix & match the Marvel/DDP series, I can't help but wonder who would've been suited for a GI Joe Reloaded film.
My picks thus far:
General Stanson: Tommy Lee Jones or Hugo Weaving.: I really liked that Gen. Stanson was portrayed as a Man in Black cold fish in the Reloaded run, and both Tommy Lee Jones & Hugo Weaving would be a natural in the role.
Hawk: David Caruso : Yeah, I like CSI Miami over the main series. And Mr. Caruso can bring it off as Hawk's younger in Reloaded.
Scarlett: Uma Thurman: After Kill Bill, I think Uma should've been cast over Rachel Nichols in the coming film-thankfully, Reloaded's a far more serious series.
Rock 'N Roll: Kiefer Sutherland - as Jack Bauer, he already deals with terrs on 24. Just add a goatee, and he's a natch for GI Joe's resident SEAL.
Beach Head: Connor Trineer: Lt. Cmdr. Trip Tucker on Star Trek Enterprise. As the Xindi arc proves, Connor can shift from happy go lucky to dead serious as the role demands.
Snake Eyes: This is gonna be tricky as unlike the Marvel run, we never got to see what SE even looks like in the Reloadedverse. My best bet for now is Daniel Craig.
Stalker: Will Smith: the Pursuit of Happyness & the Legend of Bagger Vance proved he can tackle serious roles. And there's I Am Legend...
Doc: Halle Berry:And why not? She can play serious and action roles.
Duke: Ralph Fiennes: As Duke in Reloaded is far easier to like in Reloaded than at DDP, the former John Steed can play him.
Lady J: This is also a bit of a trick as LJ is way more attractive & easier to like than she was in the Marvel/DDP run...Maybe Jessica Alba?

Storm Shadow: Ken Watanabe from Memoirs of A Geisha.
Destro: Tom Hardy -Preator Shinzon from Star Trek Nemesis
Cobra Commander: Robert Downey, Jr. As Tony Stark, he proved he can play a man who has a humane side with an intellectual bent. Unlike DDP's CC, the Reloaded version of the Commander isn't a madman. He's a thinking terrorist.
The Baroness: Kate Beckinsale: Since the coming movie conveniently ignored that Anastascia's a European, time to correct that oversight.

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"In war, there can be no sustitute for victory."
-General of the Army Douglas MacArthur
"Speak your mind. After all, it's a free country."
-Captain America
"Risk is our business."
-Captain James T. Kirk

Thought about this for a while, and frankly it kind of falls in line with how I would have cast ANY G.I. Joe movie. In many cases the Reloaded characters are the core versions, free of convoluted continuity. Let's face facts, I love Larry Hama's run on Marvel, but there's an awful lot of contrivance and coincidence to keep those stories going (so, Baroness believes Snakes killed her bother in 'Nam AND it so happens it was CC's brother who killed Snake's family, AND Storm Shadow turns out to have a history with Snakes AND... well, you get the idea). Reloaded brought us the heart of those characters, which was what we should have seen in a movie, rather than trying so hard to tie everyone together (so, Baroness was engaged to Duke AND her brother was Duke's best friend, AND it so happens that Rex becomes Cobra Commander, AND... well, you get the idea). So, here's my suggestions for casting G.I. Joe: Reloaded, which I still hope somehow makes it back to us again.

Duke: Howie Long- a little older, a little jaded, and certainly a bit of a bruiser while still being damn smart. I watched Howie make a reference to Sisyphus while doing Super Bowl commentary once. Left Terry Bradshaw scratching his head.

Cobra Commander- You need the right voice to say, "I am the Cobra Commander, and you are the rat." I vote Kevin Spacey. His voice conveys quiet mania beautifully.

Scarlett- Laura Prepon; she's pretty without being supermodel gorgeous, nearly six feet tall so you buy into her physicality, and can convey not taking crap from anyone. I will admit Rachel Nichols wasn't a bad choice, but she has the unfortunate baggage of having been in Rise of Cobra.

Destro- Gary Oldman. Plain and simple.

Baroness- Ten years ago, I'd have said Sherilyn Fenn, but time has passed. Olivia Wilde proved her Baroness look in "Ballad of GI Joe," I'd love to see her pull off the accent. And there has to be an accent...

Snake Eyes- Ray Park can stay, but no lips.

Stalker- Michael Jai White cna bring some "Black Dynamite" cool to Stalker.

Rock and Roll- bulk up Justin Timberlake and give him a beard. Like him or not, he's got acting chops and can pull off our troubled Navy Seal just fine.

Hawk- He's a full bird, he's not a kid. Kurt Russell.

Storm Shadow- I may have to agree with Ken Watanabe above. Good choice.

Lady Jaye- Hmmm... Slightly younger, very attractive but tough. Possibly Erica Durance who plays Lois Lane on Smallville. She can pull off a little snotty too.

Doc- Gina Torres, who should be allowed to be in all movies anyway, but knows how to play solid.

Just my thoughts!

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WWCCD?

Not bad choices at all!

Too bad Reloaded movie won't happen until I win the lottery... few times