9. Tony Mendez
For years, "cue card boy" Tony Mendez's shtick on Dave's show was that he was hilariously, unreasonably surly about everything. ("I look like a jolly person," he said, smiling, while looking straight into the camera during his web series The Tony Mendez Show. "But inside, I'm filled with rage.") He'd had a very different life before becoming the host's punching bag: Born in Cuba in 1945, Mendez was a ballet dancer, and he'd appeared in Broadway shows like Pippin. But after joining Letterman's NBC show in 1993 and then accompanying him to his CBS gig, the stagehand started to appear onscreen more often (see his oddball "broken glass in the chocolate" skit), especially as Dave seemed to enjoy belittling the man. Unfortunately, the story does not end happily: The comedic tension Mendez brought to his bits spilled over into real life when he was fired from the show in 2014 after assaulting staff writer Bill Scheft during an argument.