An actor with his heart in rock and The D

Before he played Barry, the in-your-face record store clerk in “High Fidelity” (2000), Jack Black was busy strumming, singing and writing playful songs for his mock-rock group, Tenacious D.

Black formed the comedy duo in 1994 with Kyle Gass, a fellow actor he’d met in Tim Robbins’ the Actors’ Gang. Naming themselves after a term used by sportscaster Marv Albert (“The Knicks are playing some tenacious D!”), they created a pair of good-hearted goofballs called Jables and KG, who think they are the “greatest band on Earth.”

They once described “the D” as the “two-headed love child” of heavy metal pioneers Black Sabbath, Iron Maiden and Molly Hatchet. Others saw them as a cross between Wayne’s World and Spinal Tap, performing acoustic “folk metal” songs about sex, rock legends and myths, devil worship and sex.

Through sweaty, hard-rocking club performances around Hollywood, TV appearances on Saturday Night Live, “Mr. Show,” and a short-lived 1999 HBO series, they built an international following and launched several sell-out tours.

Pursuing their acting careers meanwhile, Gass and Black acted together in Robbins’ “The Cradle Will Rock” and “Bio-Dome.” As Black’s career took off with numerous TV performances and feature films (“Saving Silverman,” “Shallow Hal,” “Orange County”), he and Gass continued to perform as “the D” for loyal fans. Their first CD was released last year.

On Oct. 21, Epic Records will release “Tenacious D -- the Complete Masterworks,” a DVD collection that features a Nov. 3, 2002, recital at London’s Brixton Academy, where they performed their best-known songs: “Tribute,” “Wonderboy,” “Kielbasa,” “Dio” and a tongue-in-cheek tune exhorting men to treat their lovers gently now and then.

“School of Rock” isn’t the first film in which Black has contributed to the soundtrack. In “High Fidelity,” he performed his own rendition of Marvin Gaye’s “Let’s Get It On” as lead singer of the fictional Sonic Death Monkeys.

Like his comic acting style, which has been compared to Robin Williams’ and John Belushi’s, Black is known to give his all to his energetic live performances.

Amid all of Black’s kidding on the set of “The School of Rock,” the words his young rocker/actor co-stars remember most were probably the most telling: “Rock is my passion,” he told them. “Acting is my bread and butter.”

-- Lynn Smith