Hiring of a big-name actor to play a supporting role. The idea is usually that the actor's fame will draw in viewers, as it normally would if you put them prominently on the advertising; but you don't have to pay them as much if they only have to do a few days work. Sometimes it's a compromise, for when the studio heads wanted big stars playing the main characters. This can also work for documentaries with the casting of the narrator. Examples of Stunt Casting include: