Basically someone says a actors name who is NOT in Harry Potter and the next person fits them to the best role for them! It's based on what they look like really! (easier if you include picture of the actor)
If you don't know who the actor is just look them up on google and find a picture if one hasn't been posted!
YOU CAN use the same actor again because someone else might see them in a different role!
OH and the actors can be dead or alive!
So I'll start off: Johnny Depp
then the next person picks the character he'd play best then a new actor! :)