Over the past few weeks and months, speculations of what "The Fallen" actually is. I have done plenty of research and I have come to my conclusion. It is a character that we haven't seen in the film. It is the actual character that was in the War Within comics. I believe they probably have redesigned him to suit the director's vision but this is what I think based on what we know and have heard.
Apparently, a lot of filming was done in Egypt and according to Bay, there will be scenes of the transformers who came to Egypt before the pyramids were built. Based on that I am assuming that this means some of the original transformers will be present. For us who know the orgin of the Fallen, we know he was one of the original thirteen transformers.
He's also one of the "mystical" characters in the franchise and as we all know, new comer Ehren Kruger was brought on board for his knowledge of the mythology of the transformers. We will add on the fact that Orci has said that he would like to introduce Mr Unicron to the third installation. Hmmm....how would you lead up to that? Who let that guy out his cage? Oh yeah.....THE FALLEN!
With this being said, I would have to say that I expect the fallen to actually be The Fallen. On top of that, I expect to see Primus in this film. Not certain though. But maybe that's the giant bot we see in the commercial. Hmmmmm?