^{The Beatles in 1965. Source: Wikipedia}

Elvis Presley is widely hailed as the King of Rock and Roll, but in 1966 John Lennon said the Beatles were "more popular than Jesus" in a London Evening Standard interview.

Based on record sales, this Wikipedia article and this Business Insider article of top music acts would certainly seem to bear that out (but Wiki has the caveat that several mega-artists are not included in their list).

Elvis may always be the King, but the Beatles outsold him considerably, and may well have been "more popular than Jesus" with the popular culture youth in the 1960's. But has any music act in modern history (20th to 21st centuries) ever been bigger than the Beatles (worldwide, in number of recordings sold, on any and all media including wax, vinyl, tape, CD, and digital downloads)?