1. Shredder: Henry Golding
In all of the TMNT movies so far, Shredder has been a one-dimensional villain, with very little speaking lines and no real motive behind his actions. However, I think that casting Henry Golding in the role could change that.
Golding emerged as a huge star last year, and I think that he has what it takes to be a popular action star. He is in excellent shape, and while I don’t know if we’ve ever seen him play a character that is supposed to be as menacing as Shredder, I think that he could pull it off excellently.