When filmmakers decide to make a historical flick, whether it's a biopic or something focused on a particular event or era, they usually try to cast actors who look like the original historical figures.
Sometimes the addition of prosthetics and a specially made wardrobe is needed to really sell the role, but more often than not the successful portrayal of a well-known figure starts with the right famous face.
It's an actor's job to become the characters they portray, whether real or fictional, but it seems like some actors were born to play a role, like a reincarnation of the original soul.