The presence of Rocket Raccoon in the Marvel cinematic universe is a risky prospect. A walking, talking raccoon has the potential to undermine everything that has gone on so far in the Marvel cinematic universe. Don't get me wrong, I'm aware that the advanced technology, gods, magic and monsters that we've seen so far are hardly 'realistic', but an anthropomorphic raccoon wielding high-tech firearms could just be a step too far. If Rocket Raccoon is going to be prominent (which it seems he is), his portrayal needs to be appropriate and able to fit in with the likes of Iron Man and Captain America. At this moment in time, it's hard to imagine the mammal interacting with such characters and being able to take the interactions seriously. Primarily, Marvel and Disney need to cast an actor who can pull it off. I'm not even sure what kind of actor is required for such a role, and it's very hard to envision, but an actor known solely or predominantly for comedic roles (such as the likes of Jim Carrey and Adam Sandler - both of whom have been mentioned) could make the character impossible to invest in. David Tennant seems the most likely man to be cast, given the rumours, and I can see this working. Tennant has the capacity to make people laugh - of that there is no doubt - but he can also be serious and dramatic. He could be the man to ensure Rocket Raccoon is a success on screen.