1. Fin Fang Foom
When I first saw the gigantic metal dragon in the trailers for The Avengers, I rubbed my hands with delight as I was confident that it would be a new-age take on Fin Fang Foom, one of Iron Man's classic antagonists who has yet to appear in the MCU. Though he'd be a difficult one to get right if they went with a literal dragon, there are, of course, plenty of ways to make it work - especially considering the fact that Ant-Man and possibly Wasp are now entering the franchise - and it would give Tony Stark a more interesting challenge beyond the human realm. Poring over the comics will reveal links between The Mandarin and Foom, so it's not inconcievable to believe that we could see him sleeping in a cave or something at the end of Iron Man 3. Perhaps he will awaken, we'll see him slither away and that's all she wrote (for now). It'd be a tough sell, but one I'd totally admire their ambition for attempting. We shall see. Who would you most like to see cameo in Iron Man 3? Let us know in the comments below.