Markoe describes The David Letterman Show, which ran in the mornings on NBC from June through October 1980, as a "4 mo. pilot" for Late Night in a video posted to Letterman's revamped YouTube channel. "For me, you can't get to Late Night without stumbling through what the morning show was," says Markoe, who was also head writer of The David Letterman Show. She adds: "I say this over and over again, it was really a bath of fire for me." ALSO: Markoe shares a telegram Martin Scorsese sent from the Raging Bull set mourning The David Letterman Show's cancelation.