4. Tim Curry
I mean for one thing, he's not in the best of health recently, recovering from a massive stroke so while he will make a full recovery his future in front of a camera or on a stage remains yet to be seen. Also, like with Head, the trend of consistently younger actors stepping into the role would cease (Smith is now 30; Curry 67). But most importantly, as great an actor as Curry is, he's almost too good, like creepy good; he played It the Clown for crying out loud! The dude gave most kids and even some adults nightmares with one of the scariest horror movie performances of all time and he would be playing the Doctor! Call me prejudiced if you will but, wow.