Maybe this has been done before. Anyway, if Sentinels had a big budget movie like the Avengers, who would you want to play the heroes?
Tempest - Doug Jones
The Scholar - Phillip Seymour Hoffman
Those are the only two that I can think of at the moment...
Kate Micucci as the Wraith ! Please ! 
Her buddy Riki Lindhome could be Tachyon.
Jack Black as the Scholar.
William H. Macy as Legacy, as strange as it seems 
And Reverend Ivan Stang as Baron Blade 
Edit : Let's add Lawrence Makoare as Haka and Andy Serkis as Absolute Zero.
Don't know much about the scholar since I'm not a playtester. I think Jack Black could pull off the wacky, quirkly aspects of the character, but my interpretation of the character is that under the eccentricity is a dignified wisdom that I think could be pulled off by Hoffman, and Hoffman could definitely do the wacky too as anyone who's seen the Big Lebowski can tell you.
Garfunkle and Oates!? That would be awesome!
Agreed, Nielzabub - I just used the opportunity to toss the name of people I like, as my knowledge of today's actors is very limited. And by the way : Sam Rockwell as Bunker ?
Both ladies seem like they would be able to pull off the look for both characters without much trouble.
I think Sam Rockwell could pull off a decent Bunker.
I am always for more Sam Rockwell, but I think he would be a bit too old for the role.
…Not that I actually have any idea of who could pull it off. Shock… 
I feel the urge to add a Yukulele equipment card to the Wraith's deck.
Sorry for both the double post and not taking this casting seriously enough, Nielzabub.
For Citizen Dawn, what would you think of Cate Blanchett or Claudia Christian ?
I'm going to go with Claudia Christian, mostly because I love Babylon 5. Claudia has a really strong stage presence and is always charming even when her character is being a complete jerk, which I think would be perfect for someone like Dawn.
Blanchett as Dawn, Christian as The Assistant.
Don't know much about Assistant other than she can really kill you, but that sounds like solid casting.
The playtesting forums don't really give much more insight on a character than what is provided on the Kickstarter. The Hero or Villain M.O. is established through the cards, but their hopes, dreams, and appearance are easily accessed by everyone with their bios and pictures.
I think Nathan Fillion could actually pull off a decent Legacy. He has the chin and is actually about the right age.
No, he's pretty much set as Captain Hammer.
That's why it's called acting. 
I think Nathan's a great choice, but then I'm a Browncoat… 
Ron Glass for Mr. Fixer? 
I'm not saying he couldn't pull it off, but it would be awfully confusing.. I mean, we're supposed to LIKE Legacy, aren't we?
Ron Glass as Fixer seems pretty obvious, yes. Then again, you could probably fit the whole cast of Firefly somewhere in the Multiverse...
There's always room for Alan Tudyk, before he's impaled.