Elvis Presley may be the single most important figure in American 20th century popular music. Not necessarily the best, and certainly not the most consistent. But no one could argue with the fact that he was the musician most responsible for popularizing rock & roll on an international level. Viewed in cold sales figures, his impact was phenomenal. Dozens upon dozens of international smashes from the mid-'50s to the mid-'70s, as well as the steady sales of his catalog and reissues since his death in 1977, may make him the single highest-selling performer in history.