Here's my entry (you probably need to click on it to see the whole thing):
The actors went through a rigorous audition process, with up to three actors contesting some roles. They were chosen as a result of their proven abilities to play their roles with conviction, physical similarities to the character, or substantial financial bribes to the casting agency.
(faces morphed with Morph Thing, then put back onto the bodies and some classic Hollywood-esque photoshopping then went on mostly colour matching to bodies etc).
Here's the raw Morph Thing heads (again, click to see them all):
And here's a closer look at the casts: