7. Spinal Tap – May 5, 1984

Before This Is Spinal Tap became a cult classic, Spinal Tap performed two songs and appeared in a filmed bit with the episode’s host Barry Bostwick to promote the film’s release. Interesting fact: the bit went so well that the show’s producer at the time Dick Ebersol approached the three actors/members to join the cast. Christopher Guest and Harry Shearer (aka Nigel Tufnel and  Derek Smalls) accepted the offer and joined the cast a few months later for only one season. Meanwhile, Michael McKean (aka David St. Hubbins) initially turned down the offer but would join the SNL cast ten years later.