4. The Wasp
One of the more plausible characters to be making an appearance in Iron Man 3 is The Wasp; so plausible, in fact, that she could end up with a role that exceeds that of a cameo. When Stephanie Szostak (Dinner for Schmucks) was cast in a nameless role last summer, rumours began to swirl that she had been cast as The Wasp, with various Tweets and cryptic rumours implying that she is playing a character of sure significance. What's particularly telling is that Szostak is receiving surprisingly prominent billing for what otherwise would probably be a cursory supporting role; we're figuring she has some sort of bearing on the bigger picture moving towards The Avengers 2. Though the idea of The Wasp would be difficult to imagine coinciding with a lot of what we've seen so far in the MCU, the sheer fact that Ant-Man is confirmed to be partaking in the fun shows that Kevin Feige isn't afraid of throwing these goofy bug-related characters into the mix. The fact that in one of the trailers you can see her pushing Tony into a wall has me thinking she's not just going to be a forgettable female who Tony has to deal with.