I'd say Will Smith has been pretty popular, since 1986 when Jazzy Jeff & The Fresh Prince came out, to his movie career today. Even Jackie Chan is known worldwide, it doesn't just have to be a music star. In music, it probably won't happen. It's different today. If they were starting out today I don't think MJ, Prince, The Beatles, U2, Elvis, Madonna, Led Zepplin, Jimi Hendrix, etc would be that popular. Back then, acts played in clubs, fairs or whatever for years before they were discovered and had time to really develop. There was no internet or instant success. A lot of acts were on small start up labels because the majors didn't want to experiment or bother with niche genres. When such genres became popular - like jazz, rock & roll, blues, folk, country - the major lables bought them out and the mom & pop labels who didn't have the funds or distribution muscle of the majors and went out of business. Majors mostly had very mainstream stuff like Perry Como or Tony Bennett. The Beatles were turned down by several labels, but they had a manager Brian Epstein who really believed in them and didn't give up. BB King sang for over 2 decades before he really crossed over. Some acts were popular because of the time period they came out like Simon & Garfunkel, Nat King Cole, Yes, or Motley Crue.