Marilyn Manson (the person whose real name is Brian Warner, not the band), was on The O'Reilly Factor once. He pretty much won the argument, while still done up. Not only did he win an argument with the king of interrupting you and not letting you speak, he did it without changing a thing about himself.
Even more, the two seem to have a fairly civil chat, with O'Reilly admitting that Manson is very well-spoken (and after that, minimizes interrupting him when he makes a point), and Manson admitting that Bill brings up valid points against him and that he respects him for challenging his views. The thing that makes this the most awesome is that he made Bill O'Reilly, who, as mentioned above, likes to steamroll over his guests and sometimes talk down to them, seemingly back down from what he probably assumed was going to be a shouting match.
Marilyn Manson himself appeared on MTV on a program called Mothers Against Manson, in which he engaged in discussion with the concerned parents of two of his teenaged female fans. One mom's beef with Manson was that her daughter had turned away from Catholicism since becoming a Marilyn Manson fan. To this, Manson replied very calmly and not unkindly, "Maybe it's your religion, and it wasn't supposed to be hers."
Manson's appearance in Michael Moore's Bowling for Columbine where Moore interviewed him in response to accusations that his music had helped drive the Columbine killers to commit their massacre. Manson was completely calm and level-headed and when Moore asked him what he would say to the killers if he had the chance, he responded "I wouldn't say anything; I'd just listen to what they had to say, and that's what no one did." Best moment in the movie, right there.
This is more of a moment for Manson's unlikely friends than Manson himself, but in an episode of Politically Incorrect with Bill Maher in the 1990s, Manson gets lambasted by Lakita Garth, who insisted that she was more Christ-like than he was. Finally, Manson defends himself, and when Garth tries to condescend again, Florence Henderson jumps to his defense:
Henderson: Maybe he's more Christ-like than you are.
Manson's appearance on Once Upon a Time as the voice of The Neverland Shadow pretty much emobdies the term One-Scene Wonder (despite being in two scenes). Dark, creepy, and everything you would expect the Shadow to sound like if it could talk. Well done, Mr. Manson.