This Is Spinal Tap is a 1984 American mockumentary comedy film directed by Rob Reiner in his feature directorial debut. Christopher Guest, Michael McKean, and Harry Shearer play members of the parody heavy metal band Spinal Tap, while Reiner plays Martin "Marty" Di Bergi, a documentary filmmaker following the band on tour. The film satirizes the behavior and musical pretensions of rock bands and hagiographic rock documentaries such as Led Zeppelin's The Song Remains the Same (1976) and the Band's The Last Waltz (1978) (as Eric Idle and Neil Innes had done for the Beatles with the Rutles). Reiner, Guest, McKean, and Shearer are credited with writing the screenplay, though most of the dialogue was improvised and dozens of hours were filmed.