1. Bob Dylan
Bob Dylan completely changed how the music world perceived great singers. Before Dylan hit the scene in the early Sixties, great singers had to have traditional voices. People like Frank Sinatra had hits, and people with voices like Dylan wrote the songs and stayed behind the scenes. Dylan changed all that, ushering in the singer-songwriter era. His voice has gone through countless permutations over the years. He sounds like a weary old man on his 1962 debut LP, and just four years later he sounded like a speed-addled maniac on his 1966 European tour with The Band. He quit smoking and discovered a whole new twangy voice for Nashville Skyline in 1969, and he sang with unbridled intensity on the 1975/'76 Rolling Thunder tour. By the early Nineties Dylan's voice had evolved into the endlessly parodied nasal sound we all associate with Dylan, which has since devolved even further into the guttural bark he has today. Many of these voices sound like they couldn't possibly come from the same man – and yet they're all distinctly Bob Dylan.