If you have seen Star Trek, put down the remote and switch to Heroes, where this actor really earned his stripes. The average writing made his character flip flop motivation so many times, I would kill to see him play a straight arrow like Jim Raynor. The scruff and beat down look would work, and he already has the presence to command a room from playing Spock in the recent Star Trek flick. He really could be the troubled marshal fighting for what little he can.
His face really fits the profile, and after seeing Iron Man, he can play dual character that goes from a revolutionary to dictator without missing a step.
Matt Horner - Justin Long
Respectability? Check. Young and a bit niave, but knows the difference between right and wrong? Check. Guiding light? Check. Based on some of his more serious roles, and not just his commercials, I have no doubt in my mind he could pull off the good angel on the shoulder of Jim Raynor.
Tycus Findlay - Jason StathamHe shoots stuff and is gruff and intimidating. Use he in reference to either Statham or Findlay.
Sarah Kerrigan - Kate BeckinsaleThe Underworld films tell me she can play the gun toting bad ass. But the Queen bitch of the Universe? Yeah, she can do that too. Her death stare in Underworld is spooky as hell, and with the right make-up artist, the Queen of Blades could really come out in her performance. Honestly, screw CG for this one, maybe the wings, but in full costume and make-up, I feel she could really blow this away.
I think Cillian can totally pull of being the child to Jeff Bridges. The character arc works well too, because he is using his corrupt father's resources to establish himself as being his own man and perusing what he wants. It is a shame that this character is considered 'new' to players of the games, but the books really give him the depth that Cillian Murphy would channel into an awesome character.
This guy is a fantastic actor in his own right, and this role is something he could pull off. Cold, calculating, and an arrogance from being psychic is something he could solidify with just a glace. In the game Tosh is an enigma who holds his secrets close to his chest, and based on Serenity alone (let alone Children of Men), Chiwetel can definitely pull this off.
Duran - Isaiah Mustafa
Better known to the internet as "Old Spice Man", this role would totally redefine him. Evil, brooding, and possibly going to shoot you in the head, I would love to see Isaiah in a more serious role. While Duran's role in the Starcraft universe has yet to be fleshed out, I think Isaiah could take that opportunity and put his own unique flair on the character.