Did Johnny Cash really kill someone?

No, Johnny Cash did not kill anyone. While he had a tumultuous life and struggled with personal demons, including substance abuse, there are no records or evidence to suggest that he was involved in any homicide. Cash did, however, famously write and perform songs about themes of violence and regret, which may have contributed to the misconception. His song "Folsom Prison Blues," for example, reflects the perspective of a man imprisoned for murder, but it's a work of fiction.