Harvey Pekar (August 31, 1988)
In the early days of Late Night, Letterman made his name aligning himself with cool outsiders — R.E.M., Andy Kaufman — but those relationships weren't always cozy. Now perhaps best known because of the movie made about him, American Splendor (starring Paul Giamatti), comic book artist Harvey Pekar delivered numerous hostile appearances on the show. The curmudgeon-vs-curmudgeon battle peaked with his 1988 interview, where he went off on General Electric, NBC's bosses at the time, and called Dave "a shill" for the company. It irritated Dave enough that he vowed to ban Pekar. "I'd rather be liked than thought of as a crazy man," the late artist told the Los Angeles Times in 1995, "but with Letterman, I've been in a situation where you either lay down and let him insult you or you do something about it. Most people keep their mouth shut and let him dump on them. I don't wanna do that."