Rob Halford and James Hetfield represent two of the most influential voices in heavy music history. Halford, frontman of Judas Priest, redefined what a metal singer could do with his wide vocal range and piercing high screams that became a blueprint for generations. His theatrical delivery made Priest legendary. Hetfield of Metallica built a different path. His aggressive growl and powerful rhythm-driven delivery powered thrash metal into stadiums and gave Metallica its unstoppable identity. Hal