Characters make surprise appearances in comic book movies all the time - if anything, random cameos are expected. The MCU is no exception, as evidenced by Tony Stark popping up in The Incredible Hulk, Hawkeye dropping by to point an arrow at Thor's head in Thor and Bruce Banner turning up in Iron Man 3 to sleep through all of Tony' s drama. With Captain America: Civil War already looking jam-packed full of all the available actors from Phases One and Two, it's not too much of a stretch to imagine that Kevin Feige will be looking to include one or two surprises along the way. Hey, if they can shoehorn their new Spider-Man in there as well as introduce Black Panther, one more character isn't going to make too much of a difference. It could even be a solid storytelling move setting up a character for a future appearance down the line. With the Civil War looking to involve any people running around out there with powers and colourful tights, it stands to reason that a whole host of heroes we've seen already (or are yet to see) could make some sort of token appearance. So who are the likeliest suspects?