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 fictional heavy metal band Spinal Tap. Reiner plays Martin "Marty" Di Bergi, a documentary filmmaker following the band's American tour. The film satirizes the behavior and musical pretensions of rock bands and the hagiographic tendencies of rock documentaries such as The Song Remains the Same and The Last Waltz,

Reiner, Guest, McKean, and Shearer wrote the screenplay, though most of the dialogue was improvised and dozens of hours were filmed.

Credited with launching the mockumentary genre,^, it is also notable as the origin of the phrase "up to eleven". Deemed "culturally, historically, or aesthetically significant" by the Library of Congress, it was selected for preservation in the National Film Registry in 2002.

The Internet Movie Database normally allows users to rate films only up to ten stars, but specifically for Spinal Tap, the site allows users to rate the film eleven stars.