2. Bruce Banner/Hulk
Rumours of Hulk's potential in the TV world have been floating around for a while now and what better way to test the water for a full-on Hulk TV series than have him guest star on Agents of Shield. The story pretty much writes itself, Hulk running amok in New York while all his super-buds are away somewhere, so Shield has to deal with it in-house. The more you think about it, the more likely it seems. Marvel already has a character model for Hulk so there wouldn't have to be such a vast budget for visual effects and also Joss Whedon seems to know how to use the character well. He isn't just a monster in The Avengers, he is a human just going through a rough patch. By smashing things.