Tenacious D is an American comedy rock duo formed in Los Angeles, in 1994. It was founded by actors Jack Black and Kyle Gass, who were then members of The Actors' Gang theater company. The duo's name is derived from "tenacious defense", a phrase used by NBA basketball sportscasters Walt Frazier and Marv Albert. Backing members include John Konesky, John Spiker, and Scott Seiver. Dave Grohl has recorded drums and percussion on all studio albums, but does not perform live.

Kyle Richard Gass is an American musician, singer and actor, best known for co-founding—and being a member of—Tenacious D, a Grammy-winning comedy band. He is also a member of Trainwreck and the Kyle Gass Band.