Thanos has been confirmed for the film and it's rumored that The Other will be returning with the surviving Chitauri. While the character Death is only briefly hinted to in his Avengers cameo it's possible she could be involved as well. Going on the run could very well mean the Guardians have stolen something of great importance. A few sites have speculated the items of interest would be the Infinity Gems (each has their own power) which could lead them to Adam Warlock and make them the most wanted people in the universe. When combined with the Infinity Gauntlet (currently in Odin's vault) the wearer becomes extremely powerful with the ability to control space and time. Thanos plans to use the gauntlet to kill half the universe as a romantic offering to Death.
Rumors that Nova Corps. will be playing a major role in the film have been circling online. The ships in the background of the concept art are possibly Nova ones. It makes sense the Nova Corps. could be the jailers and are now on the trail of the ex-cons (Guardians). Richard Rider seems like a solid cosmic character that could be trying to track down the Guardians.
James recently tweeted this image of a prop from the film which is teasing (also confirming?) Guardian member Cosmo. The Head of Security for Knowhere, the space station where the Guardians have made their homebase. He's a talking Russian dog with powers that include telepathy and telekinesis. It will be interesting to see how Cosmo fits into the film or if he just ends up a cameo or get's cut out altogether. Cosmo first appeared in Nova #8, it's just another reason to think he'll show up.
ORIGINS/CHARACTER DESIGNS UPDATED: It's being reported the team will get character updates along with their designs to fit the cinematic universe. Star-Lord will spend some time without his iconic mask/helmet as mentioned by Marvel artist Steve McNivens who is talking with the studio about their look. We've seen a similar change to Thor wearing his helmet less often in the films. Since you need to see an actor's face to see him emote a performance. Plus, it can be very difficult to shoot action scenes with something that heavy on your face/head. Not many high profiled actors would have been willing to sign-on only for their face to be covered-up for a majority of the film.
Another tidbit coming from LatinoReview who claim that Star-Lord, Drax and Gamora will see a shake up of their origins to fit the film better. The green skinned heroes more so because of their connections with Thanos. Gamora has a past with Adam Warlock which could mean we might see him too. I assume the pair will also see their barely clothed character designs updated. Nothing has been mentioned concerning Groot but I expect to hear him say more than "I Am Groot!".
SILVER SURFER, IRON MAN, STARK INDUSTRIES AND SWORD?: Apparently, during the talks between Marvel and Fox over the rights of Daredevil it was brought up that Marvel Studios wanted to use Silver Surfer and Galactius for Guardians. The bargaining tactic didn't exactly work as the Daredevil rights were left to revert back to Marvel. However, unless Fox has a Fantastic Four film in production sometime between 2013-2014 those rights could also come back to Marvel/Disney. That would open the door to all sorts of awesome storylines and expansion of the cosmic world.
Oddly, enough even though we've been hearing how separate the Guardians will be from the Avengers films a new rumor conflicts with that. As there is a rumor of Iron Man showing up at some point in the film. I imagine that Peter Quill's spaceship and tech could actually come from Stark Industries. Quill's origin is already being updated, so seeing him apart of SWORD wouldn't be a giant leap to make. Seeing Stark show up in the beginning to see his test pilot (Quill) off with an experimental ship would make sense. This could possibly lead to S.W.O.R.D. being setup and the introduction to Abigail Brand which were both created by Joss Whedon. Another theory is that the new Guardians comic series is going to be more in-line with what the film will look like. Iron Man outfitted with an outerspace friendly suit being a member of the team.
CASTING HOPEFULS: There haven't been any serious casting announcements made for the film but a couple of names have been put forth. Michael Rooker (Walking Dead) and MC Chris (Aqua Teen Hunger Force) are campaigning for the role of Rocket Raccoon. While he's been given a gruff Cockney voice in recent cartoons and video games it seems like he could lose the accent. Gunn regular Rooker spoke to about the chances of him landing a role in the film to Collider. While he had originally mentioned wanting to play Rocket, this time he mentions voicing Groot as an option as well.
"All of them. I’d play the racoon guy. I’d play the tree guy. They’re all very cool characters! But, I don’t know. Marvel and Gunn have their own thing going on. It’s very secretive. Until they decide, it’s very secretive. I don’t know any inside scoop, or anything like that. But, we talk. We’re still friends, so we hang out and talk. Whenever I’m in town, we get together. So, I know he’s very busy and working real hard on the rewrite and getting everything set to go. It’s always a pleasure to work with him, so whatever happens, happens."
"I would. Oh, yeah, sure! I’d have a lot of fun with it. I did a little interview earlier and had a similar question, and now it’s all over the internet that I’m campaigning for a role. All I said was, “Yeah, that would be cool!,” but now I’m campaigning. Dammit, I want that role! The fans really like the idea. I’ve noticed that. I did the interview, they showed it on the internet and, before I knew it, all my people were Tweeting it and posting it on Facebook. They’re interested in having me be a part of it, in some way."
"Gunn is always thinking of his friends and the people that he’s worked with. He’s quite a loyal director, and he’s a good friend, as well. He’s always, “Well, maybe Rooker can do this one. I think he’d like to do this.” I’m sure he’s thought of me, so we’ll see. Marvel has their agenda. Everyone has their own agenda, trying to get it cast and get it cast well. It’s going to be cool. I’m glad he’s involved with it. It’s a great, fun project. He’s a big fan! He’s been a huge fan of Marvel stuff since he was 12 years old, and even younger than that, I’m sure."
Kevin Smith recently tweeted that MC Chris (a rapper/voice actor) should voice Rocket. It led to Chris putting together a campaign on Facebook. I have to admit both choices are excellent but Chris' voice is beyond unique (super awesome when he gets angry). I'd love to see Rooker play Groot with Chris Ward voicing Rocket but nothing is for sure here.
Scott Porter (Friday Night Lights) who tested for Steve Rogers in Captain America: The First Avenger over the summer put it out to MTV he wants to play Nova. While nothing has been confirmed it's looking very likely that Nova Corps and Nova will be featured in the film. Porter might have an in with the studio from testing previously for Captain America and hasn't been discouraged by that original outcome.
"Marvel just announced that they're doing 'Guardians of the Galaxy,' which is another property that I love. I read it growing up...I'd love to play Nova or another [cosmic character]."
"Gunn is a unique choice. I think he could be a really great shepherd for that property," added Porter. "I think 'Guardians' is going to be a lot of fun. I think it'll be very cool. I thought the next thing I might try and go after is 'Heroes for Hire,' but it looks like 'Guardians' is around, so..."
A lot of Nathan Fillion (Firefly) fans had assumed that he'd end up with a role being a close friend of Gunn's. After being apart of both James' Super and Slither it wouldn't be hard to imagine Nathan would be asked to join the film. Rumors started online that he was wanted for the lead role of Star-Lord. That had been dismissed by Fillion who recently stated to MTV that he was going to be too busy focusing on his series Castle. Previously, he came out said he had zero desire to play Ant-Man even before the film's official announcement this summer.
"I'm very busy right now with a job that I'm grateful for," Fillion told the site when asked about possibly starring in Guardians of the Galaxy. "I've made a commitment [to 'Castle'] and I have to see it through. And I'm really happy to."
"We had dinner the other night and he told me all about it, before everyone found out. I was on the inside on that one. Over some toro, tuna belly, we discussed how excited he is, how nervous he is, but how he wanted it very badly. He wanted it very badly. I think it's in very capable hands. It's in the right hands. Having worked with the man, I know what he's capable of."