When you consider the length of the career, the quality of the output and the influence on others, an argument can be made that Johnny Cash is the musician of the 20th century.
http://www.youtube.com/watch?v=v7gV5C5mB7A
http://www.youtube.com/watch?v=It7107ELQvY
http://www.youtube.com/watch?v=HGhCsznO0S8
http://www.youtube.com/watch?v=JMll6TNnTs4
http://www.youtube.com/watch?v=We1BVMmcr2A
http://www.youtube.com/watch?v=EtbuUlSGXzc
http://www.youtube.com/watch?v=v7gV5C5mB7A
http://www.youtube.com/watch?v=It7107ELQvY
http://www.youtube.com/watch?v=HGhCsznO0S8
http://www.youtube.com/watch?v=JMll6TNnTs4
http://www.youtube.com/watch?v=We1BVMmcr2A
http://www.youtube.com/watch?v=EtbuUlSGXzc