Olivia Newton-John

Olivia Newton-John skillfully made the transition from popular country-pop singer to popular mainstream soft rock singer, becoming one of the most successful vocalists of the '70s in the process. The transition itself wasn't much of a stretch -- her early-'70s hits "I Honestly Love You" and "Have You Never Been Mellow" were country only in the loosest sense -- yet the extent of her success in both fields was remarkable. As a country singer, her first five charting singles all went Top Ten in the U.S.; as a pop singer, she had no less than 15 Top Ten hits, including five number one singles, highlighted by "Physical," which spent ten weeks at number one in 1981 and 1982. Newton-John's sweet voice suited both country-pop and soft rock perfectly, which is what kept her at the top of the charts until the mid-'80s.