Marty DiBergi is a fictional character portrayed by actor Rob Reiner in the mockumentary film This Is Spinal Tap. He serves as the director and narrator of the film, which follows the fictional British rock band Spinal Tap on their disastrous American tour. DiBergi's character is known for his earnest yet often clueless demeanor, providing a humorous lens through which the band's antics are showcased. In the film, DiBergi interviews band members and captures their experiences, highlighting the absurdities of the music industry. His interactions with David St. Hubbins, Nigel Tufnel, and Derek Smalls contribute to the film's satirical take on rock culture, making him an essential part of the story.