Actually, before there ever was Tenacious D, Jack Black had small parts in television shows like Life Goes On, Northern Exposure, and The X-Files in the same episode that had Giovanni Ribisi, and was a regular on the HBO series Mr. Show. His first film was the Tim Robbins film Bob Roberts. He was in other films such as Demolition Man, The Neverending Story III, Bio-Dome, Cable Guy, The Jackal in which he is killed by Bruce Willis, and a whole lot of others. So, he's been around for a while, it just wasn't until High Fidelity that he REALLY got noticed by mainstream America.