CriminalxMinds @ LJ

Technically, the person who pwns the bit part topic is Jonathan Frakes. One two-minute scene and he`s forever immortalized by the Smackdown of All Time. I`m not sure that scene would have been as impactful if an unknown had done it. But I know that`s not quite what you want - you want the unknowns, so at the top of my list of people who managed to make their one moment their own: the waitress who asked Gideon how he would know when he found what he was looking for (there was just something in her tone); the clown`s dad in "Limelight" (his pathos and desperation to excuse/help his son was heart-rending), and the prostitute who hit on Reid (her flirting, and not being put off by Reid`s obliviousness, ultimately leading to true curiosity about what he was talking about).