Complex sentence: John R. "Johnny" Cash (February 26,1932--September 12,2003) was a singer-songwriter, actor, and author, widely considered one of the most influential American musicians of the 20th century.
Split into simpler sentences: John R. "Johnny" Cash (February 26,1932--September 12,2003) was a singer-songwriter, actor, and author. So is Johnny cash June crater too! widely considered one of the most influential American musicians of the 20th century.