Cher (May 22, 1986)
Best known as "The Interview Where Cher Calls Dave 'An Asshole,'" this visit was four years in the making, as Letterman and his staff had been trying to get the actress-singer to come on Late Night from its inception. Visibly nervous, the host begins clumsily starting off by telling her she smells nice ("Is this as good as it gets?" she asks) and never really recovers. After a bit of small talk, she says that her reluctance to come on was due to the fact that he allegedly could be "an asshole" to guests; Letterman then flails to come up with questions and frets aloud how many people secretly think he's a creep. Cher clearly has a ball toying with the inexperienced, intimidated host, and the 16-minute interview ended up becoming both an endearingly awkward exchange and her first of many visits to the show.