Which guitarist was known for his 'boom-chicka-boom' style in Johnny Cash's band?

The guitarist known for the "boom-chicka-boom" style in Johnny Cash's band was Luther Perkins.

Perkins was a founding member of Cash's early backing group, the Tennessee Two, alongside bassist Marshall Grant. When drummer W. S. "Fluke" Holland joined later, the group became the Tennessee Three. Perkins's restrained, rhythmic guitar playing became one of the defining sounds of Cash's recordings and live performances.

His approach emphasized space and pulse rather than elaborate solos. He often muted the lower strings with the heel of his picking hand, creating a clipped, percussive rhythm that supported Cash's vocals without competing with them. The sound became widely described as "boom-chicka-boom" or "boom-chicka-boom," especially in the group's Sun Records recordings and later performances.

Perkins was born in 1928 and worked as an automobile mechanic in Memphis before meeting Cash. He played on many important Cash recordings, including the live performance later heard on Johnny Cash at Folsom Prison. Perkins died in 1968, after which Bob Wootton became Cash's principal lead guitarist. Marshall Grant was the bassist, and W. S. Holland was the drummer, so neither is the canonical answer to this question.