Very important. They are the ones who bring the real - life characters to the screen. A good cast can make the story believable and engaging.
The cast is of great significance in a true - story movie. They are like the bridge between the real - life events and the audience. If the cast doesn't perform well, the movie might not be able to capture the essence of the true story. Take a movie about a famous scientist. If the actor playing the scientist doesn't seem intelligent or curious enough, it can break the illusion for the viewers. Good casting can make a true - story movie a great success.