4. Hawkeye
Easily the worst character in the first Avengers movie, Hawkeye spent a good portion of the flick as Loki's zombified lackey, causing actor Jeremy Renner to even lament his role, citing that it wasn't what he signed on for. Though this sparked rumours that Hawkeye might either be written out of the MCU entirely or possibly recast, the current word is that Renner is back as Hawkeye, and that Joss Whedon has been working hard to ensure that his character gets a stronger arc this time around. A meatier focus on Hawkeye could, of course, mean that he ends up sacrificing himself in some way for the cause. This would work for a number of reasons - a) Nobody likes the character enough to be super-p*ssed off about it and b) It would make the looming relationship between Black Widow and Captain America - if rumours are to be believed - far less awkward, with her prior love interest promptly taken out of commission. Plus, one can't put it past Marvel to be vindictive and kill the character off just because they don't like what the actor playing him said about the last movie.
Chance Of It Happening: 5/10