Final answer:
Bob Dylan is the musician who transformed himself from the quintessential folk protest artist into a major force in American rock music.
Step-by-step explanation:
The musician who transformed himself from the quintessential folk protest artist into a major force in American rock music was Bob Dylan. Dylan, a 1960s-era artist, spoke to many cultures and generations about injustice and the need for inclusion and change. His songs, such as "The Times They Are a-Changin'", influenced the thoughts and perspectives of his fans and played a significant role in the civil rights movement and opposition to the Vietnam War.