5. Julia Roberts
When Julia Roberts first came on Late Night, she was 22 and had just appeared in Mystic Pizza and was promoting Steel Magnolias. During the interview, she kept being harassed by a bubble-eating dog, and Daryl Hannah showed up impromptu. It would be the last time Roberts would be upstaged on Dave’s show. The host's greatest flirting partner, Roberts recognized the chemistry she had with Letterman, milking their rapport over a series of memorable encounters that doubled as an unrequited love affair. "I love the woman in a way you can on television," Letterman told his audience during a 2001 broadcast. And when Dave married his longtime girlfriend Regina Lasko in 2009, Roberts coyly informed him, "I don't know if I can look you in the eye anymore … Last time I saw you, you were single and then I, like, hypnotized you in my white suit or something and you went off and married Regina."