Let's do a little mental exercise. Think about one of your favorite movie characters of all time. Picture the way they move, the way they talk, their family background. Everything. Think of their most perfect line of dialogue. Now, chances are, a wiry screenwriter was probably hunched over their keyboard, carefully fleshing out every detail of this character's personality and crafting the dialogue that will eventually be repeated (and probably misquoted) for years to come. And in a lot of cases, that's probably a pretty accurate picture of how these characters were born. A few of them, however, weren't created until the actor playing them showed up on the set for that day's run-throughs. Because even though the majority of Hollywood's most enduring movies are carefully crafted, some of them don't even have a finished script when the cameras first start rolling. That lack of structure--with the right actors and a director who isn't afraid to let things happen naturally--can be responsible for bringing fresh, interesting characters to life. Characters that might have otherwise faded into oblivion.