The role of the casting director is often overlooked in Hollywood. But now the profession is getting the spotlight in a new documentary, Casting By, which premieres tonight on HBO. It tells the story of the birth of the casting profession, in the late 1950s led by two of the first casting directors Lynn Stalmaster and Marion Doughtery. For his casting work on The Thomas Crown Affair, Stalmaster was the first person to receive the "casting by" credit that became standard in main title credits ever after. Yet, casting directors, who just last week were given an official branch in the Academy of Motion Picture Arts and Sciences, are not eligible to be nominated for Academy Awards. While every film is a collaborative effort, without casting directors, movies we all know and love might look quite different. A casting director has the power to pluck an unknown actor from obscurity and turn them into a star, to revive the career of a has-been, or to change the tone and direction of a movie altogether. In the slide show above, seven casting decisions that almost didn’t happen that gave us unforgettable movie roles and moments.