Tenacious D is a rock band from Los Angeles, California. The band consists of musicians and actors Jack Black (vocals, guitar) and Kyle Gass (guitar, vocals).

Tenacious D formed in 1994 when the members performed as an acoustic duo. The band first gained popularity in 1999 when they starred in their eponymous television series and began to support large rock acts. In 2001, they released Tenacious D, their debut album featuring a full band. The first single, "Tribute", was the band's most successful achieving their only Top 10 in any chart, until they released "The Metal", which was first shown at Saturday Night Live. In 2006, they starred in, and recorded the soundtrack for, Tenacious D in The Pick of Destiny. In support of the film, the band went on a world tour, appearing for the first time with a full band.

Tenacious D's music showcases Black's theatrical vocal delivery and Gass' acoustic guitar playing abilities. Critics have described their fusion of vulgar absurdist comedy with rock music as "mock rock". Their songs discuss the duo's purported musical and sexual prowess, as well as their friendship and cannabis usage in a style that music critics have compared with the storyteller-style lyrics of rock opera.