Brian Baker was one of the founding members of the seminal hardcore punk rock band Minor Threat. He first played bass, but in 1982 moved to guitar when Steve Hansgen joined the band, then back to bass after Hansgen's departure. He later formed Dag Nasty in 1985, had stints in: Doggy Style, The Meatmen (with fellow Minor Threat member Lyle Preslar), Government Issue, and Junkyard (a hard rock band). In 1994, he was offered a touring spot with R.E.M. but declined, accepting instead an offer to replace Brett Gurewitz as a guitarist in Bad Religion, alongside guitarist Greg Hetson.