It’s got to be difficult enough to simply stand there in front of all those people and equipment and play costume make-believe. So that must go double the moment you’re asked to interact with anything that isn’t there, such as a big CGI dinosaur or any given Andy Serkis role. Worse than that, there are also times when actors have to play both sides of a conversation. Not only do they have to pretend to interact with an imaginary role – but also play that imaginary role interacting right back at them. It sounds complicated, so here are some of the best instances.