Gotta be a part for Karl Urban. The dude is a one man SF&F acting school. He nailed Bones in ST, he nailed Eomer in LOTR, he's starring in awesome looking new SF Copshow 'Almost Human' and of course he IS JUDGE DREDD!

JJ needs to get him the lead role just so he can have some kind super SF franchise full house. Plus the higher his star rises the more chance of Dredd 2! He's so badass that he even has a comic book alter-ego called 'Urb Karlan' who is an actor in SF&F films from the future!